**STILLBAKING** Decouple disk cache tests from backends.

net/disk_cache/simple/simple_unittest.cc

Index: net/disk_cache/simple/simple_unittest.cc
diff --git a/net/disk_cache/simple/simple_unittest.cc b/net/disk_cache/simple/simple_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..846f831e62b024cf1ba47330dcfcadd971b36943
--- /dev/null
+++ b/net/disk_cache/simple/simple_unittest.cc
@@ -0,0 +1,1792 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <set>
+#include <string>
+
+#include "base/file_util.h"
+#include "base/platform_file.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+#include "net/base/io_buffer.h"
+#include "net/base/test_completion_callback.h"
+#include "net/disk_cache/backend_tests.h"
+#include "net/disk_cache/cache_util.h"
+#include "net/disk_cache/disk_cache_test.h"
+#include "net/disk_cache/disk_cache_test_util.h"
+#include "net/disk_cache/entry_tests.h"
+#include "net/disk_cache/simple/simple_backend_impl.h"
+#include "net/disk_cache/simple/simple_index.h"
+#include "net/disk_cache/simple/simple_entry_format.h"
+#include "net/disk_cache/simple/simple_entry_impl.h"
+#include "net/disk_cache/simple/simple_synchronous_entry.h"
+#include "net/disk_cache/simple/simple_test_util.h"
+#include "net/disk_cache/simple/simple_util.h"
+#include "base/single_thread_task_runner.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace disk_cache {
+
+namespace {
+
+class SimpleCacheCreateBackendExtraData
+    : public BackendTestTraits::CreateBackendExtraData {
+ public:
+  SimpleCacheCreateBackendExtraData() : do_not_wait_for_index_(false) {}
+
+  bool do_not_wait_for_index() const { return do_not_wait_for_index_; }
+  void set_do_not_wait_for_index(bool do_not_wait_for_index) {
+    do_not_wait_for_index_ = do_not_wait_for_index;
+  }
+
+ private:
+  bool do_not_wait_for_index_;
+};
+
+class SimpleCacheBackendTraits : public BackendTestTraits {
+ public:
+  virtual ~SimpleCacheBackendTraits() {}
+
+  virtual Backend* CreateBackend(
+      const CreateBackendExtraData* extra_data,
+      const base::FilePath& cache_path,
+      int max_size,
+      base::MessageLoopProxy* task_runner) const OVERRIDE {
+    const SimpleCacheCreateBackendExtraData* simple_cache_extra_data =
+        static_cast<const SimpleCacheCreateBackendExtraData*>(extra_data);
+
+    net::TestCompletionCallback cb;
+    scoped_ptr<SimpleBackendImpl> simple_backend(
+        new SimpleBackendImpl(
+            cache_path, max_size, type_,
+            make_scoped_refptr(task_runner).get(), NULL));
+    int rv = simple_backend->Init(cb.callback());
+    if (cb.GetResult(rv) != net::OK)
+      return NULL;
+    if (simple_cache_extra_data &&
+        !simple_cache_extra_data->do_not_wait_for_index()) {
+      net::TestCompletionCallback wait_for_index_cb;
+      rv = simple_backend->index()->ExecuteWhenReady(
+          wait_for_index_cb.callback());
+      if (wait_for_index_cb.GetResult(rv) != net::OK)
+        return NULL;
+    }
+    return simple_backend.release();
+  }
+
+  virtual bool UsesCacheThread() const OVERRIDE { return false; }
+  virtual bool ImplementsCouldBeSparse() const OVERRIDE { return false; }
+  virtual bool DoomedSparseEntriesIOWorks() const OVERRIDE { return false; }
+
+  virtual void AddDelay() const OVERRIDE {
+    // The simple cache uses second resolution for many timeouts, so it's safest
+    // to advance by at least whole seconds before falling back into the normal
+    // disk cache epsilon advance.
+    const base::Time initial_time = base::Time::Now();
+    do {
+      base::PlatformThread::YieldCurrentThread();
+    } while (base::Time::Now() -
+             initial_time < base::TimeDelta::FromSeconds(1));
+    
+    BackendTestTraits::AddDelay();
+  }
+
+  virtual bool SetMaxSize(Backend* backend, int size) const OVERRIDE {
+    return static_cast<SimpleBackendImpl*>(backend)->SetMaxSize(size);
+  }
+
+  net::CacheType cache_type() const { return type_; }
+
+  static const BackendTestTraits* DiskCache() {
+    static SimpleCacheBackendTraits traits(net::DISK_CACHE);
+    return &traits;
+  }
+
+  static const BackendTestTraits* AppCache() {
+    static SimpleCacheBackendTraits traits(net::DISK_CACHE);
+    return &traits;
+  }
+
+ private:
+  explicit SimpleCacheBackendTraits(net::CacheType type) : type_(type) {}
+
+  const net::CacheType type_;
+};
+
+INSTANTIATE_TEST_CASE_P(
+    SimpleCache, DiskCacheEntryTest,
+    ::testing::Values(SimpleCacheBackendTraits::DiskCache(),
+                      SimpleCacheBackendTraits::AppCache()));
+
+INSTANTIATE_TEST_CASE_P(
+    SimpleCache, DiskCacheBackendTest,
+    ::testing::Values(SimpleCacheBackendTraits::DiskCache(),
+                      SimpleCacheBackendTraits::AppCache()));
+
+class DiskCacheSimpleEntryTest : public DiskCacheTest {
+ protected:
+  net::CacheType cache_type() const { return simple_traits()->cache_type(); }
+
+ private:
+  const SimpleCacheBackendTraits* simple_traits() const {
+    return
+        static_cast<const SimpleCacheBackendTraits*>(DiskCacheTest::traits());
+  }
+};
+
+INSTANTIATE_TEST_CASE_P(
+    SimpleCache, DiskCacheSimpleEntryTest,
+    ::testing::Values(SimpleCacheBackendTraits::DiskCache(),
+                      SimpleCacheBackendTraits::AppCache()));
+
+class DiskCacheSimpleBackendTest : public DiskCacheTest {};
+
+INSTANTIATE_TEST_CASE_P(
+    SimpleCache, DiskCacheSimpleBackendTest,
+    ::testing::Values(SimpleCacheBackendTraits::DiskCache(),
+                      SimpleCacheBackendTraits::AppCache()));
+
+// Individual unit tests and helper functions after here.
+
+bool MakeBadChecksumEntry(const std::string& key,
+                          DiskCacheTest* test,
+                          int* out_data_size) {
+  disk_cache::Entry* entry = NULL;
+
+  if (test->CreateEntry(key, &entry) != net::OK || !entry) {
+    LOG(ERROR) << "Could not create entry";
+    return false;
+  }
+
+  const char data[] = "this is very good data";
+  const int kDataSize = arraysize(data);
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kDataSize));
+  base::strlcpy(buffer->data(), data, kDataSize);
+
+  EXPECT_EQ(kDataSize, test->WriteData(entry, 1, 0, buffer.get(), kDataSize, false));
+  entry->Close();
+  entry = NULL;
+
+  // Corrupt the last byte of the data.
+  base::FilePath entry_file0_path = test->cache_path().AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
+  int flags = base::PLATFORM_FILE_WRITE | base::PLATFORM_FILE_OPEN;
+  base::PlatformFile entry_file0 =
+      base::CreatePlatformFile(entry_file0_path, flags, NULL, NULL);
+  if (entry_file0 == base::kInvalidPlatformFileValue)
+    return false;
+
+  int64 file_offset =
+      sizeof(disk_cache::SimpleFileHeader) + key.size() + kDataSize - 2;
+  EXPECT_EQ(1, base::WritePlatformFile(entry_file0, file_offset, "X", 1));
+  if (!base::ClosePlatformFile(entry_file0))
+    return false;
+  *out_data_size = kDataSize;
+  return true;
+}
+
+// Tests that the simple cache can detect entries that have bad data.
+TEST_P(DiskCacheSimpleEntryTest, BadChecksum) {
+  InitCache();
+
+  const char key[] = "the first key";
+  int size_unused;
+  ASSERT_TRUE(MakeBadChecksumEntry(key, this, &size_unused));
+
+  disk_cache::Entry* entry = NULL;
+
+  // Open the entry.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kReadBufferSize = 200;
+  EXPECT_GE(kReadBufferSize, entry->GetDataSize(1));
+  scoped_refptr<net::IOBuffer> read_buffer(new net::IOBuffer(kReadBufferSize));
+  EXPECT_EQ(net::ERR_CACHE_CHECKSUM_MISMATCH,
+            ReadData(entry, 1, 0, read_buffer.get(), kReadBufferSize));
+}
+
+// Tests that an entry that has had an IO error occur can still be Doomed().
+TEST_P(DiskCacheSimpleEntryTest, ErrorThenDoom) {
+  InitCache();
+
+  const char key[] = "the first key";
+  int size_unused;
+  ASSERT_TRUE(MakeBadChecksumEntry(key, this, &size_unused));
+
+  disk_cache::Entry* entry = NULL;
+
+  // Open the entry, forcing an IO error.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kReadBufferSize = 200;
+  EXPECT_GE(kReadBufferSize, entry->GetDataSize(1));
+  scoped_refptr<net::IOBuffer> read_buffer(new net::IOBuffer(kReadBufferSize));
+  EXPECT_EQ(net::ERR_CACHE_CHECKSUM_MISMATCH,
+            ReadData(entry, 1, 0, read_buffer.get(), kReadBufferSize));
+
+  entry->Doom();  // Should not crash.
+}
+
+bool TruncatePath(const base::FilePath& file_path, int64 length)  {
+  const int flags = base::PLATFORM_FILE_WRITE | base::PLATFORM_FILE_OPEN;
+  base::PlatformFile file =
+      base::CreatePlatformFile(file_path, flags, NULL, NULL);
+  if (base::kInvalidPlatformFileValue == file)
+    return false;
+  const bool result = base::TruncatePlatformFile(file, length);
+  base::ClosePlatformFile(file);
+  return result;
+}
+
+TEST_P(DiskCacheSimpleEntryTest, NoEOF) {
+  InitCache();
+
+  const char key[] = "the first key";
+
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  disk_cache::Entry* null = NULL;
+  EXPECT_NE(null, entry);
+  entry->Close();
+  entry = NULL;
+
+  // Force the entry to flush to disk, so subsequent platform file operations
+  // succed.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  entry->Close();
+  entry = NULL;
+
+  // Truncate the file such that the length isn't sufficient to have an EOF
+  // record.
+  int kTruncationBytes = -implicit_cast<int>(sizeof(disk_cache::SimpleFileEOF));
+  const base::FilePath entry_path = cache_path().AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
+  const int64 invalid_size =
+      disk_cache::simple_util::GetFileSizeFromKeyAndDataSize(key,
+                                                             kTruncationBytes);
+  EXPECT_TRUE(TruncatePath(entry_path, invalid_size));
+  EXPECT_EQ(net::ERR_FAILED, OpenEntry(key, &entry));
+}
+
+TEST_P(DiskCacheSimpleEntryTest, NonOptimisticOperationsBasic) {
+  // Test sequence:
+  // Create, Write, Read, Close.
+  
+  // APP_CACHE doesn't use optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::APP_CACHE);
+  InitCache();
+  disk_cache::Entry* const null_entry = NULL;
+
+  disk_cache::Entry* entry = NULL;
+  EXPECT_EQ(net::OK, CreateEntry("my key", &entry));
+  ASSERT_NE(null_entry, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kBufferSize = 10;
+  scoped_refptr<net::IOBufferWithSize> write_buffer(
+      new net::IOBufferWithSize(kBufferSize));
+  CacheTestFillBuffer(write_buffer->data(), write_buffer->size(), false);
+  EXPECT_EQ(
+      write_buffer->size(),
+      WriteData(entry, 1, 0, write_buffer.get(), write_buffer->size(), false));
+
+  scoped_refptr<net::IOBufferWithSize> read_buffer(
+      new net::IOBufferWithSize(kBufferSize));
+  EXPECT_EQ(read_buffer->size(),
+            ReadData(entry, 1, 0, read_buffer.get(), read_buffer->size()));
+}
+
+TEST_P(DiskCacheSimpleEntryTest, NonOptimisticOperationsDontBlock) {
+  // Test sequence:
+  // Create, Write, Close.
+
+  // APP_CACHE doesn't use optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::APP_CACHE);
+  InitCache();
+  disk_cache::Entry* const null_entry = NULL;
+
+  MessageLoopHelper helper;
+  CallbackTest create_callback(&helper, false);
+
+  int expected_callback_runs = 0;
+  const int kBufferSize = 10;
+  scoped_refptr<net::IOBufferWithSize> write_buffer(
+      new net::IOBufferWithSize(kBufferSize));
+
+  disk_cache::Entry* entry = NULL;
+  EXPECT_EQ(net::OK, CreateEntry("my key", &entry));
+  ASSERT_NE(null_entry, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  CacheTestFillBuffer(write_buffer->data(), write_buffer->size(), false);
+  CallbackTest write_callback(&helper, false);
+  int ret = entry->WriteData(
+      1,
+      0,
+      write_buffer.get(),
+      write_buffer->size(),
+      base::Bind(&CallbackTest::Run, base::Unretained(&write_callback)),
+      false);
+  ASSERT_EQ(net::ERR_IO_PENDING, ret);
+  helper.WaitUntilCacheIoFinished(++expected_callback_runs);
+}
+
+TEST_P(DiskCacheSimpleEntryTest, NonOptimisticOperationsBasicsWithoutWaiting) {
+  // Test sequence:
+  // Create, Write, Read, Close.
+
+  // APP_CACHE doesn't use optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::APP_CACHE);
+  InitCache();
+  disk_cache::Entry* const null_entry = NULL;
+  MessageLoopHelper helper;
+
+  disk_cache::Entry* entry = NULL;
+  // Note that |entry| is only set once CreateEntry() completed which is why we
+  // have to wait (i.e. use the helper CreateEntry() function).
+  EXPECT_EQ(net::OK, CreateEntry("my key", &entry));
+  ASSERT_NE(null_entry, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kBufferSize = 10;
+  scoped_refptr<net::IOBufferWithSize> write_buffer(
+      new net::IOBufferWithSize(kBufferSize));
+  CacheTestFillBuffer(write_buffer->data(), write_buffer->size(), false);
+  CallbackTest write_callback(&helper, false);
+  int ret = entry->WriteData(
+      1,
+      0,
+      write_buffer.get(),
+      write_buffer->size(),
+      base::Bind(&CallbackTest::Run, base::Unretained(&write_callback)),
+      false);
+  EXPECT_EQ(net::ERR_IO_PENDING, ret);
+  int expected_callback_runs = 1;
+
+  scoped_refptr<net::IOBufferWithSize> read_buffer(
+      new net::IOBufferWithSize(kBufferSize));
+  CallbackTest read_callback(&helper, false);
+  ret = entry->ReadData(
+      1,
+      0,
+      read_buffer.get(),
+      read_buffer->size(),
+      base::Bind(&CallbackTest::Run, base::Unretained(&read_callback)));
+  EXPECT_EQ(net::ERR_IO_PENDING, ret);
+  ++expected_callback_runs;
+
+  helper.WaitUntilCacheIoFinished(expected_callback_runs);
+  ASSERT_EQ(read_buffer->size(), write_buffer->size());
+  EXPECT_EQ(
+      0,
+      memcmp(read_buffer->data(), write_buffer->data(), read_buffer->size()));
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic) {
+  // Test sequence:
+  // Create, Write, Read, Write, Read, Close.
+
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  MessageLoopHelper helper;
+  CallbackTest callback1(&helper, false);
+  CallbackTest callback2(&helper, false);
+  CallbackTest callback3(&helper, false);
+  CallbackTest callback4(&helper, false);
+  CallbackTest callback5(&helper, false);
+
+  int expected = 0;
+  const int kSize1 = 10;
+  const int kSize2 = 20;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize1));
+  scoped_refptr<net::IOBuffer> buffer1_read(new net::IOBuffer(kSize1));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize2));
+  scoped_refptr<net::IOBuffer> buffer2_read(new net::IOBuffer(kSize2));
+  CacheTestFillBuffer(buffer1->data(), kSize1, false);
+  CacheTestFillBuffer(buffer2->data(), kSize2, false);
+
+  disk_cache::Entry* entry = NULL;
+  // Create is optimistic, must return OK.
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry,
+                                base::Bind(&CallbackTest::Run,
+                                           base::Unretained(&callback1))));
+  EXPECT_NE(null, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  // This write may or may not be optimistic (it depends if the previous
+  // optimistic create already finished by the time we call the write here).
+  int ret = entry->WriteData(
+      1,
+      0,
+      buffer1.get(),
+      kSize1,
+      base::Bind(&CallbackTest::Run, base::Unretained(&callback2)),
+      false);
+  EXPECT_TRUE(kSize1 == ret || net::ERR_IO_PENDING == ret);
+  if (net::ERR_IO_PENDING == ret)
+    expected++;
+
+  // This Read must not be optimistic, since we don't support that yet.
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(
+                1,
+                0,
+                buffer1_read.get(),
+                kSize1,
+                base::Bind(&CallbackTest::Run, base::Unretained(&callback3))));
+  expected++;
+  EXPECT_TRUE(helper.WaitUntilCacheIoFinished(expected));
+  EXPECT_EQ(0, memcmp(buffer1->data(), buffer1_read->data(), kSize1));
+
+  // At this point after waiting, the pending operations queue on the entry
+  // should be empty, so the next Write operation must run as optimistic.
+  EXPECT_EQ(kSize2,
+            entry->WriteData(
+                1,
+                0,
+                buffer2.get(),
+                kSize2,
+                base::Bind(&CallbackTest::Run, base::Unretained(&callback4)),
+                false));
+
+  // Lets do another read so we block until both the write and the read
+  // operation finishes and we can then test for HasOneRef() below.
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(
+                1,
+                0,
+                buffer2_read.get(),
+                kSize2,
+                base::Bind(&CallbackTest::Run, base::Unretained(&callback5))));
+  expected++;
+
+  EXPECT_TRUE(helper.WaitUntilCacheIoFinished(expected));
+  EXPECT_EQ(0, memcmp(buffer2->data(), buffer2_read->data(), kSize2));
+
+  // Check that we are not leaking.
+  EXPECT_NE(entry, null);
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic2) {
+  // Test sequence:
+  // Create, Open, Close, Close.
+
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  MessageLoopHelper helper;
+  CallbackTest callback1(&helper, false);
+  CallbackTest callback2(&helper, false);
+
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry,
+                                base::Bind(&CallbackTest::Run,
+                                           base::Unretained(&callback1))));
+  EXPECT_NE(null, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::ERR_IO_PENDING,
+            cache()->OpenEntry(key, &entry2,
+                              base::Bind(&CallbackTest::Run,
+                                         base::Unretained(&callback2))));
+  ASSERT_TRUE(helper.WaitUntilCacheIoFinished(1));
+
+  EXPECT_NE(null, entry2);
+  EXPECT_EQ(entry, entry2);
+
+  // We have to call close twice, since we called create and open above.
+  entry->Close();
+
+  // Check that we are not leaking.
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic3) {
+  // Test sequence:
+  // Create, Close, Open, Close.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  EXPECT_NE(null, entry);
+  entry->Close();
+
+  net::TestCompletionCallback cb;
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::ERR_IO_PENDING,
+            cache()->OpenEntry(key, &entry2, cb.callback()));
+  ASSERT_EQ(net::OK, cb.GetResult(net::ERR_IO_PENDING));
+  ScopedEntryPtr entry_closer(entry2);
+
+  EXPECT_NE(null, entry2);
+  EXPECT_EQ(entry, entry2);
+
+  // Check that we are not leaking.
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry2)->HasOneRef());
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic4) {
+  // Test sequence:
+  // Create, Close, Write, Open, Open, Close, Write, Read, Close.
+
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  net::TestCompletionCallback cb;
+  const int kSize1 = 10;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize1));
+  CacheTestFillBuffer(buffer1->data(), kSize1, false);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  EXPECT_NE(null, entry);
+  entry->Close();
+
+  // Lets do a Write so we block until both the Close and the Write
+  // operation finishes. Write must fail since we are writing in a closed entry.
+  EXPECT_EQ(
+      net::ERR_IO_PENDING,
+      entry->WriteData(1, 0, buffer1.get(), kSize1, cb.callback(), false));
+  EXPECT_EQ(net::ERR_FAILED, cb.GetResult(net::ERR_IO_PENDING));
+
+  // Finish running the pending tasks so that we fully complete the close
+  // operation and destroy the entry object.
+  base::MessageLoop::current()->RunUntilIdle();
+
+  // At this point the |entry| must have been destroyed, and called
+  // RemoveSelfFromBackend().
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::ERR_IO_PENDING,
+            cache()->OpenEntry(key, &entry2, cb.callback()));
+  ASSERT_EQ(net::OK, cb.GetResult(net::ERR_IO_PENDING));
+  EXPECT_NE(null, entry2);
+
+  disk_cache::Entry* entry3 = NULL;
+  ASSERT_EQ(net::ERR_IO_PENDING,
+            cache()->OpenEntry(key, &entry3, cb.callback()));
+  ASSERT_EQ(net::OK, cb.GetResult(net::ERR_IO_PENDING));
+  EXPECT_NE(null, entry3);
+  EXPECT_EQ(entry2, entry3);
+  entry3->Close();
+
+  // The previous Close doesn't actually closes the entry since we opened it
+  // twice, so the next Write operation must succeed and it must be able to
+  // perform it optimistically, since there is no operation running on this
+  // entry.
+  EXPECT_EQ(kSize1,
+            entry2->WriteData(
+                1, 0, buffer1.get(), kSize1, net::CompletionCallback(), false));
+
+  // Lets do another read so we block until both the write and the read
+  // operation finishes and we can then test for HasOneRef() below.
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry2->ReadData(1, 0, buffer1.get(), kSize1, cb.callback()));
+  EXPECT_EQ(kSize1, cb.GetResult(net::ERR_IO_PENDING));
+
+  // Check that we are not leaking.
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry2)->HasOneRef());
+  entry2->Close();
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic5) {
+  // Test sequence:
+  // Create, Doom, Write, Read, Close.
+
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  net::TestCompletionCallback cb;
+  const int kSize1 = 10;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize1));
+  CacheTestFillBuffer(buffer1->data(), kSize1, false);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  EXPECT_NE(null, entry);
+  ScopedEntryPtr entry_closer(entry);
+  entry->Doom();
+
+  EXPECT_EQ(
+      net::ERR_IO_PENDING,
+      entry->WriteData(1, 0, buffer1.get(), kSize1, cb.callback(), false));
+  EXPECT_EQ(kSize1, cb.GetResult(net::ERR_IO_PENDING));
+
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(1, 0, buffer1.get(), kSize1, cb.callback()));
+  EXPECT_EQ(kSize1, cb.GetResult(net::ERR_IO_PENDING));
+
+  // Check that we are not leaking.
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+}
+
+TEST_P(DiskCacheSimpleEntryTest, Optimistic6) {
+  // Test sequence:
+  // Create, Write, Doom, Doom, Read, Doom, Close.
+
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  net::TestCompletionCallback cb;
+  const int kSize1 = 10;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize1));
+  scoped_refptr<net::IOBuffer> buffer1_read(new net::IOBuffer(kSize1));
+  CacheTestFillBuffer(buffer1->data(), kSize1, false);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  EXPECT_NE(null, entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  EXPECT_EQ(
+      net::ERR_IO_PENDING,
+      entry->WriteData(1, 0, buffer1.get(), kSize1, cb.callback(), false));
+  EXPECT_EQ(kSize1, cb.GetResult(net::ERR_IO_PENDING));
+
+  entry->Doom();
+  entry->Doom();
+
+  // This Read must not be optimistic, since we don't support that yet.
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(1, 0, buffer1_read.get(), kSize1, cb.callback()));
+  EXPECT_EQ(kSize1, cb.GetResult(net::ERR_IO_PENDING));
+  EXPECT_EQ(0, memcmp(buffer1->data(), buffer1_read->data(), kSize1));
+
+  entry->Doom();
+}
+
+// Confirm that IO buffers are not referenced by the Simple Cache after a write
+// completes.
+TEST_P(DiskCacheSimpleEntryTest, OptimisticWriteReleases) {
+  // Only net::DISK_CACHE runs optimistic operations.
+  TEST_DISABLED_IF(cache_type() != net::DISK_CACHE);
+
+  InitCache();
+
+  const char key[] = "the first key";
+  disk_cache::Entry* entry = NULL;
+
+  // First, an optimistic create.
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  ASSERT_TRUE(entry);
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kWriteSize = 512;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kWriteSize));
+  EXPECT_TRUE(buffer1->HasOneRef());
+  CacheTestFillBuffer(buffer1->data(), kWriteSize, false);
+
+  // An optimistic write happens only when there is an empty queue of pending
+  // operations. To ensure the queue is empty, we issue a write and wait until
+  // it completes.
+  EXPECT_EQ(kWriteSize,
+            WriteData(entry, 1, 0, buffer1.get(), kWriteSize, false));
+  EXPECT_TRUE(buffer1->HasOneRef());
+
+  // Finally, we should perform an optimistic write and confirm that all
+  // references to the IO buffer have been released.
+  EXPECT_EQ(
+      kWriteSize,
+      entry->WriteData(
+          1, 0, buffer1.get(), kWriteSize, net::CompletionCallback(), false));
+  EXPECT_TRUE(buffer1->HasOneRef());
+}
+
+TEST_P(DiskCacheSimpleEntryTest, CreateDoomRace) {
+  // Test sequence:
+  // Create, Doom, Write, Close, Check files are not on disk anymore.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  net::TestCompletionCallback cb;
+  const int kSize1 = 10;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize1));
+  CacheTestFillBuffer(buffer1->data(), kSize1, false);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  EXPECT_NE(null, entry);
+
+  EXPECT_EQ(net::ERR_IO_PENDING, cache()->DoomEntry(key, cb.callback()));
+  EXPECT_EQ(net::OK, cb.GetResult(net::ERR_IO_PENDING));
+
+  EXPECT_EQ(
+      kSize1,
+      entry->WriteData(0, 0, buffer1.get(), kSize1, cb.callback(), false));
+
+  entry->Close();
+
+  // Finish running the pending tasks so that we fully complete the close
+  // operation and destroy the entry object.
+  base::MessageLoop::current()->RunUntilIdle();
+
+  for (int i = 0; i < disk_cache::kSimpleEntryFileCount; ++i) {
+    base::FilePath entry_file_path = cache_path().AppendASCII(
+        disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, i));
+    base::File::Info info;
+    EXPECT_FALSE(base::GetFileInfo(entry_file_path, &info));
+  }
+}
+
+TEST_P(DiskCacheSimpleEntryTest, DoomCreateRace) {
+  // This test runs as APP_CACHE to make operations more synchronous. Test
+  // sequence:
+  // Create, Doom, Create.
+  TEST_DISABLED_IF(cache_type() != net::APP_CACHE);
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  net::TestCompletionCallback create_callback;
+
+  disk_cache::Entry* entry1 = NULL;
+  ASSERT_EQ(net::OK,
+            create_callback.GetResult(
+                cache()->CreateEntry(key, &entry1, create_callback.callback())));
+  ScopedEntryPtr entry1_closer(entry1);
+  EXPECT_NE(null, entry1);
+
+  net::TestCompletionCallback doom_callback;
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            cache()->DoomEntry(key, doom_callback.callback()));
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::OK,
+            create_callback.GetResult(
+                cache()->CreateEntry(key, &entry2, create_callback.callback())));
+  ScopedEntryPtr entry2_closer(entry2);
+  EXPECT_EQ(net::OK, doom_callback.GetResult(net::ERR_IO_PENDING));
+}
+
+TEST_P(DiskCacheSimpleEntryTest, DoomDoom) {
+  // Test sequence:
+  // Create, Doom, Create, Doom (1st entry), Open.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+
+  const char key[] = "the first key";
+
+  disk_cache::Entry* entry1 = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry1));
+  ScopedEntryPtr entry1_closer(entry1);
+  EXPECT_NE(null, entry1);
+
+  EXPECT_EQ(net::OK, DoomEntry(key));
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry2));
+  ScopedEntryPtr entry2_closer(entry2);
+  EXPECT_NE(null, entry2);
+
+  // Redundantly dooming entry1 should not delete entry2.
+  disk_cache::SimpleEntryImpl* simple_entry1 =
+      static_cast<disk_cache::SimpleEntryImpl*>(entry1);
+  net::TestCompletionCallback cb;
+  EXPECT_EQ(net::OK,
+            cb.GetResult(simple_entry1->DoomEntry(cb.callback())));
+
+  disk_cache::Entry* entry3 = NULL;
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry3));
+  ScopedEntryPtr entry3_closer(entry3);
+  EXPECT_NE(null, entry3);
+}
+
+TEST_P(DiskCacheSimpleEntryTest, DoomCreateDoom) {
+  // Test sequence:
+  // Create, Doom, Create, Doom.
+  InitCache();
+
+  disk_cache::Entry* null = NULL;
+
+  const char key[] = "the first key";
+
+  disk_cache::Entry* entry1 = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry1));
+  ScopedEntryPtr entry1_closer(entry1);
+  EXPECT_NE(null, entry1);
+
+  entry1->Doom();
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry2));
+  ScopedEntryPtr entry2_closer(entry2);
+  EXPECT_NE(null, entry2);
+
+  entry2->Doom();
+
+  // This test passes if it doesn't crash.
+}
+
+// Checks that an optimistic Create would fail later on a racing Open.
+TEST_P(DiskCacheSimpleEntryTest, OptimisticCreateFailsOnOpen) {
+  InitCache();
+
+  // Create a corrupt file in place of a future entry. Optimistic create should
+  // initially succeed, but realize later that creation failed.
+  const std::string key = "the key";
+  net::TestCompletionCallback cb;
+  disk_cache::Entry* entry = NULL;
+  disk_cache::Entry* entry2 = NULL;
+
+  EXPECT_TRUE(disk_cache::simple_util::CreateCorruptFileForTests(
+      key, cache_path()));
+  EXPECT_EQ(net::OK, cache()->CreateEntry(key, &entry, cb.callback()));
+  ASSERT_TRUE(entry);
+  ScopedEntryPtr entry_closer(entry);
+  ASSERT_NE(net::OK, OpenEntry(key, &entry2));
+
+  // Check that we are not leaking.
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+}
+
+// Tests that old entries are evicted while new entries remain in the index.
+// This test relies on non-mandatory properties of the simple Cache Backend:
+// LRU eviction, specific values of high-watermark and low-watermark etc.
+// When changing the eviction algorithm, the test will have to be re-engineered.
+TEST_P(DiskCacheSimpleEntryTest, EvictOldEntries) {
+  const int kMaxSize = 200 * 1024;
+  const int kWriteSize = kMaxSize / 10;
+  const int kNumExtraEntries = 12;
+  SetMaxSize(kMaxSize);
+  InitCache();
+
+  std::string key1("the first key");
+  disk_cache::Entry* entry;
+  ASSERT_EQ(net::OK, CreateEntry(key1, &entry));
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kWriteSize));
+  CacheTestFillBuffer(buffer->data(), kWriteSize, false);
+  EXPECT_EQ(kWriteSize,
+            WriteData(entry, 1, 0, buffer.get(), kWriteSize, false));
+  entry->Close();
+  AddDelay();
+
+  std::string key2("the key prefix");
+  for (int i = 0; i < kNumExtraEntries; i++) {
+    ASSERT_EQ(net::OK, CreateEntry(key2 + base::StringPrintf("%d", i), &entry));
+    ScopedEntryPtr entry_closer(entry);
+    EXPECT_EQ(kWriteSize,
+              WriteData(entry, 1, 0, buffer.get(), kWriteSize, false));
+  }
+
+  // TODO(pasko): Find a way to wait for the eviction task(s) to finish by using
+  // the internal knowledge about |SimpleBackendImpl|.
+  ASSERT_NE(net::OK, OpenEntry(key1, &entry))
+      << "Should have evicted the old entry";
+  for (int i = 0; i < 2; i++) {
+    int entry_no = kNumExtraEntries - i - 1;
+    // Generally there is no guarantee that at this point the backround eviction
+    // is finished. We are testing the positive case, i.e. when the eviction
+    // never reaches this entry, should be non-flaky.
+    ASSERT_EQ(net::OK, OpenEntry(key2 + base::StringPrintf("%d", entry_no),
+                                 &entry))
+        << "Should not have evicted fresh entry " << entry_no;
+    entry->Close();
+  }
+}
+
+// Tests that if a read and a following in-flight truncate are both in progress
+// simultaniously that they both can occur successfully. See
+// http://crbug.com/239223
+TEST_P(DiskCacheSimpleEntryTest, InFlightTruncate)  {
+  InitCache();
+
+  const char key[] = "the first key";
+
+  const int kBufferSize = 1024;
+  scoped_refptr<net::IOBuffer> write_buffer(new net::IOBuffer(kBufferSize));
+  CacheTestFillBuffer(write_buffer->data(), kBufferSize, false);
+
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+
+  EXPECT_EQ(kBufferSize,
+            WriteData(entry, 1, 0, write_buffer.get(), kBufferSize, false));
+  entry->Close();
+  entry = NULL;
+
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ScopedEntryPtr entry_closer(entry);
+
+  MessageLoopHelper helper;
+  int expected = 0;
+
+  // Make a short read.
+  const int kReadBufferSize = 512;
+  scoped_refptr<net::IOBuffer> read_buffer(new net::IOBuffer(kReadBufferSize));
+  CallbackTest read_callback(&helper, false);
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(1,
+                            0,
+                            read_buffer.get(),
+                            kReadBufferSize,
+                            base::Bind(&CallbackTest::Run,
+                                       base::Unretained(&read_callback))));
+  ++expected;
+
+  // Truncate the entry to the length of that read.
+  scoped_refptr<net::IOBuffer>
+      truncate_buffer(new net::IOBuffer(kReadBufferSize));
+  CacheTestFillBuffer(truncate_buffer->data(), kReadBufferSize, false);
+  CallbackTest truncate_callback(&helper, false);
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->WriteData(1,
+                             0,
+                             truncate_buffer.get(),
+                             kReadBufferSize,
+                             base::Bind(&CallbackTest::Run,
+                                        base::Unretained(&truncate_callback)),
+                             true));
+  ++expected;
+
+  // Wait for both the read and truncation to finish, and confirm that both
+  // succeeded.
+  EXPECT_TRUE(helper.WaitUntilCacheIoFinished(expected));
+  EXPECT_EQ(kReadBufferSize, read_callback.last_result());
+  EXPECT_EQ(kReadBufferSize, truncate_callback.last_result());
+  EXPECT_EQ(0,
+            memcmp(write_buffer->data(), read_buffer->data(), kReadBufferSize));
+}
+
+// Tests that if a write and a read dependant on it are both in flight
+// simultaneiously that they both can complete successfully without erroneous
+// early returns. See http://crbug.com/239223
+TEST_P(DiskCacheSimpleEntryTest, InFlightRead) {
+  InitCache();
+
+  const char key[] = "the first key";
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK,
+            cache()->CreateEntry(key, &entry, net::CompletionCallback()));
+  ScopedEntryPtr entry_closer(entry);
+
+  const int kBufferSize = 1024;
+  scoped_refptr<net::IOBuffer> write_buffer(new net::IOBuffer(kBufferSize));
+  CacheTestFillBuffer(write_buffer->data(), kBufferSize, false);
+
+  MessageLoopHelper helper;
+  int expected = 0;
+
+  CallbackTest write_callback(&helper, false);
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->WriteData(1,
+                             0,
+                             write_buffer.get(),
+                             kBufferSize,
+                             base::Bind(&CallbackTest::Run,
+                                        base::Unretained(&write_callback)),
+                             true));
+  ++expected;
+
+  scoped_refptr<net::IOBuffer> read_buffer(new net::IOBuffer(kBufferSize));
+  CallbackTest read_callback(&helper, false);
+  EXPECT_EQ(net::ERR_IO_PENDING,
+            entry->ReadData(1,
+                            0,
+                            read_buffer.get(),
+                            kBufferSize,
+                            base::Bind(&CallbackTest::Run,
+                                       base::Unretained(&read_callback))));
+  ++expected;
+
+  EXPECT_TRUE(helper.WaitUntilCacheIoFinished(expected));
+  EXPECT_EQ(kBufferSize, write_callback.last_result());
+  EXPECT_EQ(kBufferSize, read_callback.last_result());
+  EXPECT_EQ(0, memcmp(write_buffer->data(), read_buffer->data(), kBufferSize));
+}
+
+TEST_P(DiskCacheSimpleEntryTest, OpenCreateRaceWithNoIndex) {
+  SimpleCacheCreateBackendExtraData extra_data;
+  extra_data.set_do_not_wait_for_index(true);
+  DisableIntegrityCheck();
+  InitCacheWithExtraData(&extra_data);
+
+  // Assume the index is not initialized, which is likely, since we are blocking
+  // the IO thread from executing the index finalization step.
+  disk_cache::Entry* entry1;
+  net::TestCompletionCallback cb1;
+  disk_cache::Entry* entry2;
+  net::TestCompletionCallback cb2;
+  int rv1 = cache()->OpenEntry("key", &entry1, cb1.callback());
+  int rv2 = cache()->CreateEntry("key", &entry2, cb2.callback());
+
+  EXPECT_EQ(net::ERR_FAILED, cb1.GetResult(rv1));
+  ASSERT_EQ(net::OK, cb2.GetResult(rv2));
+  entry2->Close();
+}
+
+// Checks that reading two entries simultaneously does not discard a CRC check.
+// TODO(pasko): make it work with Simple Cache.
+TEST_P(DiskCacheSimpleEntryTest, DISABLED_SimpleCacheMultipleReadersCheckCRC) {
+  InitCache();
+
+  const char key[] = "key";
+
+  int size;
+  ASSERT_TRUE(MakeBadChecksumEntry(key, this, &size));
+
+  scoped_refptr<net::IOBuffer> read_buffer1(new net::IOBuffer(size));
+  scoped_refptr<net::IOBuffer> read_buffer2(new net::IOBuffer(size));
+
+  // Advance the first reader a little.
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  EXPECT_EQ(1, ReadData(entry, 0, 0, read_buffer1.get(), 1));
+
+  // Make the second reader pass the point where the first one is, and close.
+  disk_cache::Entry* entry2 = NULL;
+  EXPECT_EQ(net::OK, OpenEntry(key, &entry2));
+  EXPECT_EQ(1, ReadData(entry2, 0, 0, read_buffer2.get(), 1));
+  EXPECT_EQ(1, ReadData(entry2, 0, 1, read_buffer2.get(), 1));
+  entry2->Close();
+
+  // Read the data till the end should produce an error.
+  EXPECT_GT(0, ReadData(entry, 0, 1, read_buffer1.get(), size));
+  entry->Close();
+  DisableIntegrityCheck();
+}
+
+// Checking one more scenario of overlapped reading of a bad entry.
+// Differs from the |SimpleCacheMultipleReadersCheckCRC| only by the order of
+// last two reads.
+TEST_P(DiskCacheSimpleEntryTest, MultipleReadersCheckCRC2) {
+  InitCache();
+
+  const char key[] = "key";
+  int size;
+  ASSERT_TRUE(MakeBadChecksumEntry(key, this, &size));
+
+  scoped_refptr<net::IOBuffer> read_buffer1(new net::IOBuffer(size));
+  scoped_refptr<net::IOBuffer> read_buffer2(new net::IOBuffer(size));
+
+  // Advance the first reader a little.
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ScopedEntryPtr entry_closer(entry);
+  EXPECT_EQ(1, ReadData(entry, 1, 0, read_buffer1.get(), 1));
+
+  // Advance the 2nd reader by the same amount.
+  disk_cache::Entry* entry2 = NULL;
+  EXPECT_EQ(net::OK, OpenEntry(key, &entry2));
+  ScopedEntryPtr entry2_closer(entry2);
+  EXPECT_EQ(1, ReadData(entry2, 1, 0, read_buffer2.get(), 1));
+
+  // Continue reading 1st.
+  EXPECT_GT(0, ReadData(entry, 1, 1, read_buffer1.get(), size));
+
+  // This read should fail as well because we have previous read failures.
+  EXPECT_GT(0, ReadData(entry2, 1, 1, read_buffer2.get(), 1));
+  DisableIntegrityCheck();
+}
+
+// Test if we can sequentially read each subset of the data until all the data
+// is read, then the CRC is calculated correctly and the reads are successful.
+TEST_P(DiskCacheSimpleEntryTest, ReadCombineCRC) {
+  // Test sequence:
+  // Create, Write, Read (first half of data), Read (second half of data),
+  // Close.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  const int kHalfSize = 200;
+  const int kSize = 2 * kHalfSize;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer1->data(), kSize, false);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_NE(null, entry);
+
+  EXPECT_EQ(kSize, WriteData(entry, 1, 0, buffer1.get(), kSize, false));
+  entry->Close();
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry2));
+  EXPECT_EQ(entry, entry2);
+
+  // Read the first half of the data.
+  int offset = 0;
+  int buf_len = kHalfSize;
+  scoped_refptr<net::IOBuffer> buffer1_read1(new net::IOBuffer(buf_len));
+  EXPECT_EQ(buf_len, ReadData(entry2, 1, offset, buffer1_read1.get(), buf_len));
+  EXPECT_EQ(0, memcmp(buffer1->data(), buffer1_read1->data(), buf_len));
+
+  // Read the second half of the data.
+  offset = buf_len;
+  buf_len = kHalfSize;
+  scoped_refptr<net::IOBuffer> buffer1_read2(new net::IOBuffer(buf_len));
+  EXPECT_EQ(buf_len, ReadData(entry2, 1, offset, buffer1_read2.get(), buf_len));
+  char* buffer1_data = buffer1->data() + offset;
+  EXPECT_EQ(0, memcmp(buffer1_data, buffer1_read2->data(), buf_len));
+
+  // Check that we are not leaking.
+  EXPECT_NE(entry, null);
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+  entry->Close();
+  entry = NULL;
+}
+
+// Test if we can write the data not in sequence and read correctly. In
+// this case the CRC will not be present.
+TEST_P(DiskCacheSimpleEntryTest, NonSequentialWrite) {
+  // Test sequence:
+  // Create, Write (second half of data), Write (first half of data), Read,
+  // Close.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  const int kHalfSize = 200;
+  const int kSize = 2 * kHalfSize;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer1->data(), kSize, false);
+  char* buffer1_data = buffer1->data() + kHalfSize;
+  memcpy(buffer2->data(), buffer1_data, kHalfSize);
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_NE(null, entry);
+
+  int offset = kHalfSize;
+  int buf_len = kHalfSize;
+
+  EXPECT_EQ(buf_len,
+            WriteData(entry, 0, offset, buffer2.get(), buf_len, false));
+  offset = 0;
+  buf_len = kHalfSize;
+  EXPECT_EQ(buf_len,
+            WriteData(entry, 0, offset, buffer1.get(), buf_len, false));
+  entry->Close();
+
+  disk_cache::Entry* entry2 = NULL;
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry2));
+  EXPECT_EQ(entry, entry2);
+
+  scoped_refptr<net::IOBuffer> buffer1_read1(new net::IOBuffer(kSize));
+  EXPECT_EQ(kSize, ReadData(entry2, 0, 0, buffer1_read1.get(), kSize));
+  EXPECT_EQ(0, memcmp(buffer1->data(), buffer1_read1->data(), kSize));
+
+  // Check that we are not leaking.
+  ASSERT_NE(entry, null);
+  EXPECT_TRUE(
+      static_cast<disk_cache::SimpleEntryImpl*>(entry)->HasOneRef());
+  entry->Close();
+  entry = NULL;
+}
+
+// Test that changing stream1 size does not affect stream0 (stream0 and stream1
+// are stored in the same file in Simple Cache).
+TEST_P(DiskCacheSimpleEntryTest, Stream1SizeChanges) {
+  InitCache();
+  disk_cache::Entry* entry = NULL;
+  const char key[] = "the key";
+  const int kSize = 100;
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer_read(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer->data(), kSize, false);
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_TRUE(entry);
+
+  // Write something into stream0.
+  EXPECT_EQ(kSize, WriteData(entry, 0, 0, buffer.get(), kSize, false));
+  EXPECT_EQ(kSize, ReadData(entry, 0, 0, buffer_read.get(), kSize));
+  EXPECT_EQ(0, memcmp(buffer->data(), buffer_read->data(), kSize));
+  entry->Close();
+
+  // Extend stream1.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  int stream1_size = 100;
+  EXPECT_EQ(0, WriteData(entry, 1, stream1_size, buffer.get(), 0, false));
+  EXPECT_EQ(stream1_size, entry->GetDataSize(1));
+  entry->Close();
+
+  // Check that stream0 data has not been modified and that the EOF record for
+  // stream 0 contains a crc.
+  // The entry needs to be reopened before checking the crc: Open will perform
+  // the synchronization with the previous Close. This ensures the EOF records
+  // have been written to disk before we attempt to read them independently.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  base::FilePath entry_file0_path = cache_path().AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
+  int flags = base::PLATFORM_FILE_READ | base::PLATFORM_FILE_OPEN;
+  base::PlatformFile entry_file0 =
+      base::CreatePlatformFile(entry_file0_path, flags, NULL, NULL);
+  ASSERT_TRUE(entry_file0 != base::kInvalidPlatformFileValue);
+
+  int data_size[disk_cache::kSimpleEntryStreamCount] = {kSize, stream1_size, 0};
+  int sparse_data_size = 0;
+  disk_cache::SimpleEntryStat entry_stat(
+      base::Time::Now(), base::Time::Now(), data_size, sparse_data_size);
+  int eof_offset = entry_stat.GetEOFOffsetInFile(key, 0);
+  disk_cache::SimpleFileEOF eof_record;
+  ASSERT_EQ(static_cast<int>(sizeof(eof_record)), base::ReadPlatformFile(
+      entry_file0,
+      eof_offset,
+      reinterpret_cast<char*>(&eof_record),
+      sizeof(eof_record)));
+  EXPECT_EQ(disk_cache::kSimpleFinalMagicNumber, eof_record.final_magic_number);
+  EXPECT_TRUE((eof_record.flags & disk_cache::SimpleFileEOF::FLAG_HAS_CRC32) ==
+              disk_cache::SimpleFileEOF::FLAG_HAS_CRC32);
+
+  buffer_read = new net::IOBuffer(kSize);
+  EXPECT_EQ(kSize, ReadData(entry, 0, 0, buffer_read.get(), kSize));
+  EXPECT_EQ(0, memcmp(buffer->data(), buffer_read->data(), kSize));
+
+  // Shrink stream1.
+  stream1_size = 50;
+  EXPECT_EQ(0, WriteData(entry, 1, stream1_size, buffer.get(), 0, true));
+  EXPECT_EQ(stream1_size, entry->GetDataSize(1));
+  entry->Close();
+
+  // Check that stream0 data has not been modified.
+  buffer_read = new net::IOBuffer(kSize);
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  EXPECT_EQ(kSize, ReadData(entry, 0, 0, buffer_read.get(), kSize));
+  EXPECT_EQ(0, memcmp(buffer->data(), buffer_read->data(), kSize));
+  entry->Close();
+  entry = NULL;
+}
+
+// Test that writing within the range for which the crc has already been
+// computed will properly invalidate the computed crc.
+TEST_P(DiskCacheSimpleEntryTest, CRCRewrite) {
+  // Test sequence:
+  // Create, Write (big data), Write (small data in the middle), Close.
+  // Open, Read (all), Close.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  const int kHalfSize = 200;
+  const int kSize = 2 * kHalfSize;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kHalfSize));
+  CacheTestFillBuffer(buffer1->data(), kSize, false);
+  CacheTestFillBuffer(buffer2->data(), kHalfSize, false);
+
+  disk_cache::Entry* entry = NULL;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_NE(null, entry);
+  entry->Close();
+
+  for (int i = 0; i < disk_cache::kSimpleEntryStreamCount; ++i) {
+    ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+    int offset = 0;
+    int buf_len = kSize;
+
+    EXPECT_EQ(buf_len,
+              WriteData(entry, i, offset, buffer1.get(), buf_len, false));
+    offset = kHalfSize;
+    buf_len = kHalfSize;
+    EXPECT_EQ(buf_len,
+              WriteData(entry, i, offset, buffer2.get(), buf_len, false));
+    entry->Close();
+
+    ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+
+    scoped_refptr<net::IOBuffer> buffer1_read1(new net::IOBuffer(kSize));
+    EXPECT_EQ(kSize, ReadData(entry, i, 0, buffer1_read1.get(), kSize));
+    EXPECT_EQ(0, memcmp(buffer1->data(), buffer1_read1->data(), kHalfSize));
+    EXPECT_EQ(
+        0,
+        memcmp(buffer2->data(), buffer1_read1->data() + kHalfSize, kHalfSize));
+
+    entry->Close();
+  }
+}
+
+bool ThirdStreamFileExists(const base::FilePath& cache_path,
+                           const char* key) {
+  int third_stream_file_index =
+      disk_cache::simple_util::GetFileIndexFromStreamIndex(2);
+  base::FilePath third_stream_file_path = cache_path.AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(
+          key, third_stream_file_index));
+  return PathExists(third_stream_file_path);
+}
+
+// Check that a newly-created entry with no third-stream writes omits the
+// third stream file.
+TEST_P(DiskCacheSimpleEntryTest, OmittedThirdStream1) {
+  InitCache();
+
+  const char key[] = "key";
+
+  disk_cache::Entry* entry;
+
+  // Create entry and close without writing: third stream file should be
+  // omitted, since the stream is empty.
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  entry->Close();
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+
+  DoomEntry(key);
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+}
+
+// Check that a newly-created entry with only a single zero-offset, zero-length
+// write omits the third stream file.
+TEST_P(DiskCacheSimpleEntryTest, OmittedThirdStream2) {
+  InitCache();
+
+  const int kHalfSize = 8;
+  const int kSize = kHalfSize * 2;
+  const char key[] = "key";
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer->data(), kHalfSize, false);
+
+  disk_cache::Entry* entry;
+
+  // Create entry, write empty buffer to third stream, and close: third stream
+  // should still be omitted, since the entry ignores writes that don't modify
+  // data or change the length.
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_EQ(0, WriteData(entry, 2, 0, buffer, 0, true));
+  entry->Close();
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+
+  DoomEntry(key);
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+}
+
+// Check that we can read back data written to the third stream.
+TEST_P(DiskCacheSimpleEntryTest, OmittedThirdStream3) {
+  InitCache();
+
+  const int kHalfSize = 8;
+  const int kSize = kHalfSize * 2;
+  const char key[] = "key";
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer1->data(), kHalfSize, false);
+
+  disk_cache::Entry* entry;
+
+  // Create entry, write data to third stream, and close: third stream should
+  // not be omitted, since it contains data.  Re-open entry and ensure there
+  // are that many bytes in the third stream.
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_EQ(kHalfSize, WriteData(entry, 2, 0, buffer1, kHalfSize, true));
+  entry->Close();
+  EXPECT_TRUE(ThirdStreamFileExists(cache_path(), key));
+
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  EXPECT_EQ(kHalfSize, ReadData(entry, 2, 0, buffer2, kSize));
+  EXPECT_EQ(0, memcmp(buffer1->data(), buffer2->data(), kHalfSize));
+  entry->Close();
+  EXPECT_TRUE(ThirdStreamFileExists(cache_path(), key));
+
+  DoomEntry(key);
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+}
+
+// Check that we remove the third stream file upon opening an entry and finding
+// the third stream empty.  (This is the upgrade path for entries written
+// before the third stream was optional.)
+TEST_P(DiskCacheSimpleEntryTest, OmittedThirdStream4) {
+  InitCache();
+
+  const int kHalfSize = 8;
+  const int kSize = kHalfSize * 2;
+  const char key[] = "key";
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer1->data(), kHalfSize, false);
+
+  disk_cache::Entry* entry;
+
+  // Create entry, write data to third stream, truncate third stream back to
+  // empty, and close: third stream will not initially be omitted, since entry
+  // creates the file when the first significant write comes in, and only
+  // removes it on open if it is empty.  Reopen, ensure that the file is
+  // deleted, and that there's no data in the third stream.
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_EQ(kHalfSize, WriteData(entry, 2, 0, buffer1, kHalfSize, true));
+  EXPECT_EQ(0, WriteData(entry, 2, 0, buffer1, 0, true));
+  entry->Close();
+  EXPECT_TRUE(ThirdStreamFileExists(cache_path(), key));
+
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+  EXPECT_EQ(0, ReadData(entry, 2, 0, buffer2, kSize));
+  entry->Close();
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+
+  DoomEntry(key);
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+}
+
+// Check that we don't accidentally create the third stream file once the entry
+// has been doomed.
+TEST_P(DiskCacheSimpleEntryTest, OmittedThirdStream5) {
+  InitCache();
+
+  const int kHalfSize = 8;
+  const int kSize = kHalfSize * 2;
+  const char key[] = "key";
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer->data(), kHalfSize, false);
+
+  disk_cache::Entry* entry;
+
+  // Create entry, doom entry, write data to third stream, and close: third
+  // stream should not exist.  (Note: We don't care if the write fails, just
+  // that it doesn't cause the file to be created on disk.)
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  entry->Doom();
+  WriteData(entry, 2, 0, buffer, kHalfSize, true);
+  entry->Close();
+  EXPECT_FALSE(ThirdStreamFileExists(cache_path(), key));
+}
+
+// There could be a race between Doom and an optimistic write.
+TEST_P(DiskCacheSimpleEntryTest, DoomOptimisticWritesRace) {
+  // Test sequence:
+  // Create, first Write, second Write, Close.
+  // Open, Close.
+  InitCache();
+  disk_cache::Entry* null = NULL;
+  const char key[] = "the first key";
+
+  const int kSize = 200;
+  scoped_refptr<net::IOBuffer> buffer1(new net::IOBuffer(kSize));
+  scoped_refptr<net::IOBuffer> buffer2(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer1->data(), kSize, false);
+  CacheTestFillBuffer(buffer2->data(), kSize, false);
+
+  // The race only happens on stream 1 and stream 2.
+  for (int i = 0; i < disk_cache::kSimpleEntryStreamCount; ++i) {
+    ASSERT_EQ(net::OK, DoomAllEntries());
+    disk_cache::Entry* entry = NULL;
+
+    ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+    EXPECT_NE(null, entry);
+    entry->Close();
+    entry = NULL;
+
+    ASSERT_EQ(net::OK, DoomAllEntries());
+    ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+    EXPECT_NE(null, entry);
+
+    int offset = 0;
+    int buf_len = kSize;
+    // This write should not be optimistic (since create is).
+    EXPECT_EQ(buf_len,
+              WriteData(entry, i, offset, buffer1.get(), buf_len, false));
+
+    offset = kSize;
+    // This write should be optimistic.
+    EXPECT_EQ(buf_len,
+              WriteData(entry, i, offset, buffer2.get(), buf_len, false));
+    entry->Close();
+
+    ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+    EXPECT_NE(null, entry);
+
+    entry->Close();
+    entry = NULL;
+  }
+}
+
+TEST_P(DiskCacheSimpleEntryTest, TruncateLargeSparseFile) {
+  const int kSize = 1024;
+
+  // An entry is allowed sparse data 1/10 the size of the cache, so this size
+  // allows for one |kSize|-sized range plus overhead, but not two ranges.
+  SetMaxSize(kSize * 15);
+  InitCache();
+
+  const char key[] = "key";
+  disk_cache::Entry* null = NULL;
+  disk_cache::Entry* entry;
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  EXPECT_NE(null, entry);
+
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer->data(), kSize, false);
+  net::TestCompletionCallback callback;
+  int ret;
+
+  // Verify initial conditions.
+  ret = entry->ReadSparseData(0, buffer, kSize, callback.callback());
+  EXPECT_EQ(0, callback.GetResult(ret));
+
+  ret = entry->ReadSparseData(kSize, buffer, kSize, callback.callback());
+  EXPECT_EQ(0, callback.GetResult(ret));
+
+  // Write a range and make sure it reads back.
+  ret = entry->WriteSparseData(0, buffer, kSize, callback.callback());
+  EXPECT_EQ(kSize, callback.GetResult(ret));
+
+  ret = entry->ReadSparseData(0, buffer, kSize, callback.callback());
+  EXPECT_EQ(kSize, callback.GetResult(ret));
+
+  // Write another range and make sure it reads back.
+  ret = entry->WriteSparseData(kSize, buffer, kSize, callback.callback());
+  EXPECT_EQ(kSize, callback.GetResult(ret));
+
+  ret = entry->ReadSparseData(kSize, buffer, kSize, callback.callback());
+  EXPECT_EQ(kSize, callback.GetResult(ret));
+
+  // Make sure the first range was removed when the second was written.
+  ret = entry->ReadSparseData(0, buffer, kSize, callback.callback());
+  EXPECT_EQ(0, callback.GetResult(ret));
+
+  entry->Close();
+}
+
+TEST_P(DiskCacheSimpleBackendTest, SimpleCacheOpenMissingFile) {
+  InitCache();
+
+  const char* key = "the first key";
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  ASSERT_TRUE(entry != NULL);
+  entry->Close();
+  entry = NULL;
+
+  // To make sure the file creation completed we need to call open again so that
+  // we block until it actually created the files.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ASSERT_TRUE(entry != NULL);
+  entry->Close();
+  entry = NULL;
+
+  // Delete one of the files in the entry.
+  base::FilePath to_delete_file = cache_path().AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
+  EXPECT_TRUE(base::PathExists(to_delete_file));
+  EXPECT_TRUE(disk_cache::DeleteCacheFile(to_delete_file));
+
+  // Failing to open the entry should delete the rest of these files.
+  ASSERT_EQ(net::ERR_FAILED, OpenEntry(key, &entry));
+
+  // Confirm the rest of the files are gone.
+  for (int i = 1; i < disk_cache::kSimpleEntryFileCount; ++i) {
+    base::FilePath should_be_gone_file(cache_path().AppendASCII(
+        disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, i)));
+    EXPECT_FALSE(base::PathExists(should_be_gone_file));
+  }
+}
+
+TEST_P(DiskCacheSimpleBackendTest, SimpleCacheOpenBadFile) {
+  InitCache();
+
+  const char* key = "the first key";
+  disk_cache::Entry* entry = NULL;
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &entry));
+  disk_cache::Entry* null = NULL;
+  ASSERT_NE(null, entry);
+  entry->Close();
+  entry = NULL;
+
+  // To make sure the file creation completed we need to call open again so that
+  // we block until it actually created the files.
+  ASSERT_EQ(net::OK, OpenEntry(key, &entry));
+  ASSERT_NE(null, entry);
+  entry->Close();
+  entry = NULL;
+
+  // Write an invalid header for stream 0 and stream 1.
+  base::FilePath entry_file1_path = cache_path().AppendASCII(
+      disk_cache::simple_util::GetFilenameFromKeyAndFileIndex(key, 0));
+
+  disk_cache::SimpleFileHeader header;
+  header.initial_magic_number = GG_UINT64_C(0xbadf00d);
+  EXPECT_EQ(
+      implicit_cast<int>(sizeof(header)),
+      file_util::WriteFile(entry_file1_path, reinterpret_cast<char*>(&header),
+                           sizeof(header)));
+  ASSERT_EQ(net::ERR_FAILED, OpenEntry(key, &entry));
+}
+
+// Creates entries based on random keys. Stores these keys in |key_pool|.
+bool CreateSetOfRandomEntries(DiskCacheTest* test,
+                              std::set<std::string>* key_pool) {
+  const int kNumEntries = 10;
+
+  for (int i = 0; i < kNumEntries; ++i) {
+    std::string key = GenerateKey(true);
+    disk_cache::Entry* entry;
+    if (test->CreateEntry(key, &entry) != net::OK)
+      return false;
+    key_pool->insert(key);
+    entry->Close();
+  }
+
+  return
+      key_pool->size() == implicit_cast<size_t>(test->cache()->GetEntryCount());
+}
+
+// Performs iteration over the backend and checks that the keys of entries
+// opened are in |keys_to_match|, then erases them. Up to |max_to_open| entries
+// will be opened, if it is positive. Otherwise, iteration will continue until
+// OpenNextEntry stops returning net::OK.
+bool EnumerateAndMatchKeys(DiskCacheTest* test,
+                           int max_to_open,
+                           void** iter,
+                           std::set<std::string>* keys_to_match,
+                           size_t* count) {
+  Entry* entry;
+
+  while (test->OpenNextEntry(iter, &entry) == net::OK) {
+    if (!entry)
+      return false;
+    EXPECT_EQ(1U, keys_to_match->erase(entry->GetKey()));
+    entry->Close();
+    ++(*count);
+    if (max_to_open >= 0 && implicit_cast<int>(*count) >= max_to_open)
+      break;
+  };
+
+  return true;
+}
+
+// Tests basic functionality of the SimpleBackend implementation of the
+// enumeration API.
+TEST_P(DiskCacheSimpleBackendTest, EnumerationBasics) {
+  InitCache();
+  std::set<std::string> key_pool;
+  ASSERT_TRUE(CreateSetOfRandomEntries(this, &key_pool));
+
+  // Check that enumeration returns all entries.
+  std::set<std::string> keys_to_match(key_pool);
+  void* iter = NULL;
+  size_t count = 0;
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, -1, &iter, &keys_to_match, &count));
+  cache()->EndEnumeration(&iter);
+  EXPECT_EQ(key_pool.size(), count);
+  EXPECT_TRUE(keys_to_match.empty());
+
+  // Check that opening entries does not affect enumeration.
+  keys_to_match = key_pool;
+  iter = NULL;
+  count = 0;
+  disk_cache::Entry* entry_opened_before;
+  ASSERT_EQ(net::OK, OpenEntry(*(key_pool.begin()), &entry_opened_before));
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, key_pool.size()/2,
+                                    &iter,
+                                    &keys_to_match,
+                                    &count));
+
+  disk_cache::Entry* entry_opened_middle;
+  ASSERT_EQ(net::OK,
+            OpenEntry(*(keys_to_match.begin()), &entry_opened_middle));
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, -1, &iter, &keys_to_match, &count));
+  cache()->EndEnumeration(&iter);
+  entry_opened_before->Close();
+  entry_opened_middle->Close();
+
+  EXPECT_EQ(key_pool.size(), count);
+  EXPECT_TRUE(keys_to_match.empty());
+}
+
+// Tests that the enumerations are not affected by dooming an entry in the
+// middle.
+TEST_P(DiskCacheSimpleBackendTest, EnumerationWhileDoomed) {
+  InitCache();
+  std::set<std::string> key_pool;
+  ASSERT_TRUE(CreateSetOfRandomEntries(this, &key_pool));
+
+  // Check that enumeration returns all entries but the doomed one.
+  std::set<std::string> keys_to_match(key_pool);
+  void* iter = NULL;
+  size_t count = 0;
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, key_pool.size()/2,
+                                    &iter,
+                                    &keys_to_match,
+                                    &count));
+
+  std::string key_to_delete = *(keys_to_match.begin());
+  DoomEntry(key_to_delete);
+  keys_to_match.erase(key_to_delete);
+  key_pool.erase(key_to_delete);
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, -1, &iter, &keys_to_match, &count));
+  cache()->EndEnumeration(&iter);
+
+  EXPECT_EQ(key_pool.size(), count);
+  EXPECT_TRUE(keys_to_match.empty());
+}
+
+// Tests that enumerations are not affected by corrupt files.
+TEST_P(DiskCacheSimpleBackendTest, EnumerationCorruption) {
+  InitCache();
+  std::set<std::string> key_pool;
+  ASSERT_TRUE(CreateSetOfRandomEntries(this, &key_pool));
+
+  // Create a corrupt entry. The write/read sequence ensures that the entry will
+  // have been created before corrupting the platform files, in the case of
+  // optimistic operations.
+  const std::string key = "the key";
+  disk_cache::Entry* corrupted_entry;
+
+  ASSERT_EQ(net::OK, CreateEntry(key, &corrupted_entry));
+  ASSERT_TRUE(corrupted_entry);
+  const int kSize = 50;
+  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
+  CacheTestFillBuffer(buffer->data(), kSize, false);
+  ASSERT_EQ(kSize,
+            WriteData(corrupted_entry, 0, 0, buffer.get(), kSize, false));
+  ASSERT_EQ(kSize, ReadData(corrupted_entry, 0, 0, buffer.get(), kSize));
+  corrupted_entry->Close();
+
+  EXPECT_TRUE(simple_util::CreateCorruptFileForTests(key, cache_path()));
+  EXPECT_EQ(key_pool.size() + 1,
+            implicit_cast<size_t>(cache()->GetEntryCount()));
+
+  // Check that enumeration returns all entries but the corrupt one.
+  std::set<std::string> keys_to_match(key_pool);
+  void* iter = NULL;
+  size_t count = 0;
+  ASSERT_TRUE(EnumerateAndMatchKeys(this, -1, &iter, &keys_to_match, &count));
+  cache()->EndEnumeration(&iter);
+
+  EXPECT_EQ(key_pool.size(), count);
+  EXPECT_TRUE(keys_to_match.empty());
+}
+
+}  // namespace
+
+}  // namespace disk_cache