Creation of ByteStream class.

content/browser/download/byte_stream_unittest.cc

+// Copyright (c) 2012 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 "content/browser/download/byte_stream.h"
+
+#include <deque>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop.h"
+#include "base/task_runner.h"
+#include "net/base/io_buffer.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::_;
+using ::testing::Return;
+using ::testing::SaveArg;
+using ::testing::StrictMock;
+
+namespace tracked_objects {
+class Location;
+}
+
+namespace {
+
+class MockTaskRunner : public base::SequencedTaskRunner {
+ public:
+  MockTaskRunner();
+
+  // TaskRunner functions.
+  MOCK_METHOD3(PostDelayedTask, bool(const tracked_objects::Location&,
+                                     const base::Closure&, int64));
+  MOCK_METHOD3(PostDelayedTask, bool(const tracked_objects::Location&,
+                                     const base::Closure&, base::TimeDelta));
+
+  MOCK_METHOD3(PostNonNestableDelayedTask, bool(
+      const tracked_objects::Location&,
+      const base::Closure&,
+      int64 delay_ms));
+
+  MOCK_METHOD3(PostNonNestableDelayedTask, bool(
+      const tracked_objects::Location&,
+      const base::Closure&,
+      base::TimeDelta));
+
+  MOCK_CONST_METHOD0(RunsTasksOnCurrentThread, bool());
+
+ protected:
+  ~MockTaskRunner();
+};
+
+MockTaskRunner::MockTaskRunner() { }
+
+MockTaskRunner::~MockTaskRunner() { }
+
+void CountCallbacks(int* counter) {
+  ++*counter;
+}
+
+}  // namespace
+
+class ByteStreamTest : public testing::Test {
+ public:
+  ByteStreamTest();
+
+  // Create a new IO buffer of the given |buffer_size|.  Details of the
+  // contents of the created buffer will be kept, and can be validated
+  // by ValidateIOBuffer.
+  scoped_refptr<net::IOBuffer> NewIOBuffer(size_t buffer_size) {
+    scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(buffer_size));
+    char *bufferp = buffer->data();
+    for (size_t i = 0; i < buffer_size; i++)
+      bufferp[i] = (i + producing_seed_key_) % (1 << sizeof(char));
+    pointer_queue_.push_back(bufferp);
+    length_queue_.push_back(buffer_size);
+    ++producing_seed_key_;
+    return buffer;
+  }
+
+  // Create an IOBuffer of the appropriate size and add it to the
+  // ByteStream, returning the result of the ByteStream::Write.
+  // Separate function to avoid duplication of buffer_size in test
+  // calls.
+  bool Write(content::ByteStreamInput* byte_stream_input,
+             size_t buffer_size) {
+    return byte_stream_input->Write(NewIOBuffer(buffer_size), buffer_size);
+  }
+
+  // Validate that we have the IOBuffer we expect.  This routine must be
+  // called on buffers that were allocated from NewIOBuffer, and in the
+  // order that they were allocated.  Calls to NewIOBuffer &&
+  // ValidateIOBuffer may be interleaved.
+  bool ValidateIOBuffer(
+      scoped_refptr<net::IOBuffer> buffer, size_t buffer_size) {
+    char *bufferp = buffer->data();
+
+    char *expected_ptr = pointer_queue_.front();
+    size_t expected_length = length_queue_.front();
+    pointer_queue_.pop_front();
+    length_queue_.pop_front();
+    ++consuming_seed_key_;
+
+    EXPECT_EQ(expected_ptr, bufferp);
+    if (expected_ptr != bufferp)
+      return false;
+
+    EXPECT_EQ(expected_length, buffer_size);
+    if (expected_length != buffer_size)
+      return false;
+
+    for (size_t i = 0; i < buffer_size; i++) {
+      // Already incremented, so subtract one from the key.
+      EXPECT_EQ(static_cast<int>((i + consuming_seed_key_ - 1)
+                                 % (1 << sizeof(char))),
+                bufferp[i]);
+      if (static_cast<int>((i + consuming_seed_key_ - 1) %
+                           (1 << sizeof(char))) != bufferp[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+ protected:
+  MessageLoop message_loop_;
+
+ private:
+  int producing_seed_key_;
+  int consuming_seed_key_;
+  std::deque<char*> pointer_queue_;
+  std::deque<size_t> length_queue_;
+};
+
+ByteStreamTest::ByteStreamTest()
+    : producing_seed_key_(0),
+      consuming_seed_key_(0) { }
+
+// Confirm that filling and emptying the pipe works properly, and that
+// we get full triggers when we expect.
+TEST_F(ByteStreamTest, ByteStream_PushBack) {
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      3 * 1024, &byte_stream_input, &byte_stream_output);
+
+  // Push a series of IO buffers on; test pushback happening and
+  // that it's advisory.
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  EXPECT_FALSE(Write(byte_stream_input.get(), 1));
+  EXPECT_FALSE(Write(byte_stream_input.get(), 1024));
+  // Flush
+  byte_stream_input->Close(content::DOWNLOAD_INTERRUPT_REASON_NONE);
+  message_loop_.RunAllPending();
+
+  // Pull the IO buffers out; do we get the same buffers and do they
+  // have the same contents?
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_COMPLETE,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+}
+
+// Same as above, only use knowledge of the internals to confirm
+// that we're getting pushback even when data's split across the two
+// objects
+TEST_F(ByteStreamTest, ByteStream_PushBackSplit) {
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      9 * 1024, &byte_stream_input, &byte_stream_output);
+
+  // Push a series of IO buffers on; test pushback happening and
+  // that it's advisory.
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  message_loop_.RunAllPending();
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  message_loop_.RunAllPending();
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  message_loop_.RunAllPending();
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  message_loop_.RunAllPending();
+  EXPECT_FALSE(Write(byte_stream_input.get(), 6 * 1024));
+  message_loop_.RunAllPending();
+
+  // Pull the IO buffers out; do we get the same buffers and do they
+  // have the same contents?
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+}
+
+// Confirm that a Close() notification transmits in-order
+// with data on the pipe.
+TEST_F(ByteStreamTest, ByteStream_CompleteTransmits) {
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+
+  // Empty stream, non-error case.
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      3 * 1024, &byte_stream_input, &byte_stream_output);
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  byte_stream_input->Close(content::DOWNLOAD_INTERRUPT_REASON_NONE);
+  message_loop_.RunAllPending();
+  ASSERT_EQ(content::ByteStreamOutput::STREAM_COMPLETE,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_EQ(content::DOWNLOAD_INTERRUPT_REASON_NONE,
+            byte_stream_output->GetStatus());
+
+  // Non-empty stream, non-error case.
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      3 * 1024, &byte_stream_input, &byte_stream_output);
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  byte_stream_input->Close(content::DOWNLOAD_INTERRUPT_REASON_NONE);
+  message_loop_.RunAllPending();
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  ASSERT_EQ(content::ByteStreamOutput::STREAM_COMPLETE,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_EQ(content::DOWNLOAD_INTERRUPT_REASON_NONE,
+            byte_stream_output->GetStatus());
+
+  // Empty stream, non-error case.
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      3 * 1024, &byte_stream_input, &byte_stream_output);
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  byte_stream_input->Close(
+      content::DOWNLOAD_INTERRUPT_REASON_NETWORK_DISCONNECTED);
+  message_loop_.RunAllPending();
+  ASSERT_EQ(content::ByteStreamOutput::STREAM_COMPLETE,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_EQ(content::DOWNLOAD_INTERRUPT_REASON_NETWORK_DISCONNECTED,
+            byte_stream_output->GetStatus());
+
+  // Non-empty stream, non-error case.
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), message_loop_.message_loop_proxy(),
+      3 * 1024, &byte_stream_input, &byte_stream_output);
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 1024));
+  byte_stream_input->Close(
+      content::DOWNLOAD_INTERRUPT_REASON_NETWORK_DISCONNECTED);
+  message_loop_.RunAllPending();
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  ASSERT_EQ(content::ByteStreamOutput::STREAM_COMPLETE,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_EQ(content::DOWNLOAD_INTERRUPT_REASON_NETWORK_DISCONNECTED,
+            byte_stream_output->GetStatus());
+}
+
+// Confirm that callbacks on the sink side are triggered when they should be.
+TEST_F(ByteStreamTest, ByteStream_SinkCallback) {
+  scoped_refptr<MockTaskRunner> task_runner(new StrictMock<MockTaskRunner>());
+
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), task_runner,
+      10000, &byte_stream_input, &byte_stream_output);
+
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  base::Closure intermediate_callback;
+
+  // Note that the specifics of when the callbacks are called with regard
+  // to how much data is pushed onto the pipe is not (currently) part
+  // of the interface contract.  If it becomes part of the contract, the
+  // tests below should get much more precise.
+
+  // Confirm callback called when you add more than 33% of the buffer.
+
+  // Setup callback
+  int num_callbacks = 0;
+  byte_stream_output->RegisterCallback(
+      base::Bind(CountCallbacks, &num_callbacks));
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+
+  EXPECT_TRUE(Write(byte_stream_input.get(), 4000));
+  message_loop_.RunAllPending();
+
+  // Check callback results match expectations.
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_EQ(0, num_callbacks);
+  intermediate_callback.Run();
+  EXPECT_EQ(1, num_callbacks);
+
+  // Check data and stream state.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+
+  // Confirm callback *isn't* called at less than 33% (by lack of
+  // unexpected call on task runner).
+  EXPECT_TRUE(Write(byte_stream_input.get(), 3000));
+  message_loop_.RunAllPending();
+
+  // This reflects an implementation artifact that data goes with callbacks,
+  // which should not be considered part of the interface guarantee.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+}
+
+// Confirm that callbacks on the source side are triggered when they should
+// be.
+TEST_F(ByteStreamTest, ByteStream_SourceCallback) {
+  scoped_refptr<MockTaskRunner> task_runner(new StrictMock<MockTaskRunner>());
+
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      task_runner, message_loop_.message_loop_proxy(),
+      10000, &byte_stream_input, &byte_stream_output);
+
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  base::Closure intermediate_callback;
+
+  // Note that the specifics of when the callbacks are called with regard
+  // to how much data is pulled from the pipe is not (currently) part
+  // of the interface contract.  If it becomes part of the contract, the
+  // tests below should get much more precise.
+
+  // Confirm callback called when about 33% space available, and not
+  // at other transitions.
+
+  // Setup expectations and add data.
+  int num_callbacks = 0;
+  byte_stream_input->RegisterCallback(
+      base::Bind(CountCallbacks, &num_callbacks));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 2000));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 2001));
+  EXPECT_FALSE(Write(byte_stream_input.get(), 6000));
+
+  // Allow bytes to transition (needed for message passing implementation),
+  // and get and validate the data.
+  message_loop_.RunAllPending();
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  // Setup expectations.
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+
+  // Grab data, triggering callback.  Recorded on dispatch, but doesn't
+  // happen because it's caught by the mock.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  // Confirm that the callback passed to the mock does what we expect.
+  EXPECT_EQ(0, num_callbacks);
+  intermediate_callback.Run();
+  EXPECT_EQ(1, num_callbacks);
+
+  // Same drill with final buffer.
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_EQ(1, num_callbacks);
+  intermediate_callback.Run();
+  // Should have updated the internal structures but not called the
+  // callback.
+  EXPECT_EQ(1, num_callbacks);
+}
+
+// Confirm that racing a change to a sink callback with a post results
+// in the new callback being called.
+TEST_F(ByteStreamTest, ByteStream_SinkInterrupt) {
+  scoped_refptr<MockTaskRunner> task_runner(new StrictMock<MockTaskRunner>());
+
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), task_runner,
+      10000, &byte_stream_input, &byte_stream_output);
+
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  base::Closure intermediate_callback;
+
+  // Setup expectations and record initial state.
+  int num_callbacks = 0;
+  byte_stream_output->RegisterCallback(
+      base::Bind(CountCallbacks, &num_callbacks));
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+
+  // Add data, and pass it across.
+  EXPECT_TRUE(Write(byte_stream_input.get(), 4000));
+  message_loop_.RunAllPending();
+
+  // The task runner should have been hit, but the callback count
+  // isn't changed until we actually run the callback.
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_EQ(0, num_callbacks);
+
+  // If we change the callback now, the new one should be run
+  // (simulates race with post task).
+  int num_alt_callbacks = 0;
+  byte_stream_output->RegisterCallback(
+      base::Bind(CountCallbacks, &num_alt_callbacks));
+  intermediate_callback.Run();
+  EXPECT_EQ(0, num_callbacks);
+  EXPECT_EQ(1, num_alt_callbacks);
+
+  // Final cleanup.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+
+}
+
+// Confirm that racing a change to a source callback with a post results
+// in the new callback being called.
+TEST_F(ByteStreamTest, ByteStream_SourceInterrupt) {
+  scoped_refptr<MockTaskRunner> task_runner(new StrictMock<MockTaskRunner>());
+
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      task_runner, message_loop_.message_loop_proxy(),
+      10000, &byte_stream_input, &byte_stream_output);
+
+  scoped_refptr<net::IOBuffer> output_io_buffer;
+  size_t output_length;
+  base::Closure intermediate_callback;
+
+  // Setup state for test and record initiali expectations
+  int num_callbacks = 0;
+  byte_stream_input->RegisterCallback(
+      base::Bind(CountCallbacks, &num_callbacks));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 2000));
+  EXPECT_TRUE(Write(byte_stream_input.get(), 2001));
+  EXPECT_FALSE(Write(byte_stream_input.get(), 6000));
+  message_loop_.RunAllPending();
+
+  // Initial get should not trigger callback.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  message_loop_.RunAllPending();
+
+  // Setup expectations.
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+
+  // Second get *should* trigger callback.
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+
+  // Which should do the right thing when it's run.
+  int num_alt_callbacks = 0;
+  byte_stream_input->RegisterCallback(
+      base::Bind(CountCallbacks, &num_alt_callbacks));
+  intermediate_callback.Run();
+  EXPECT_EQ(0, num_callbacks);
+  EXPECT_EQ(1, num_alt_callbacks);
+
+  // Third get should also trigger callback.
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_HAS_DATA,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  EXPECT_TRUE(ValidateIOBuffer(output_io_buffer, output_length));
+  EXPECT_EQ(content::ByteStreamOutput::STREAM_EMPTY,
+            byte_stream_output->Read(&output_io_buffer, &output_length));
+}
+
+// Confirm that callback is called on zero data transfer but source
+// complete.
+TEST_F(ByteStreamTest, ByteStream_ZeroCallback) {
+  scoped_refptr<MockTaskRunner> task_runner(new StrictMock<MockTaskRunner>());
+
+  scoped_ptr<content::ByteStreamInput> byte_stream_input;
+  scoped_ptr<content::ByteStreamOutput> byte_stream_output;
+  content::CreateByteStream(
+      message_loop_.message_loop_proxy(), task_runner,
+      10000, &byte_stream_input, &byte_stream_output);
+
+  base::Closure intermediate_callback;
+
+  // Setup expectations and record initial state.
+  int num_callbacks = 0;
+  byte_stream_output->RegisterCallback(
+      base::Bind(CountCallbacks, &num_callbacks));
+  EXPECT_CALL(*task_runner.get(), PostDelayedTask(_, _, 0))
+      .WillOnce(DoAll(SaveArg<1>(&intermediate_callback),
+                      Return(true)));
+
+  // Immediately close the stream.
+  byte_stream_input->Close(content::DOWNLOAD_INTERRUPT_REASON_NONE);
+  ::testing::Mock::VerifyAndClearExpectations(task_runner.get());
+  intermediate_callback.Run();
+  EXPECT_EQ(1, num_callbacks);
+}
+
+