Fix various issues in RedirectToFileResourceHandler.

content/browser/loader/resource_loader_unittest.cc

Index: content/browser/loader/resource_loader_unittest.cc
diff --git a/content/browser/loader/resource_loader_unittest.cc b/content/browser/loader/resource_loader_unittest.cc
index d82092f8fcb274989d1fb2bb701ede01eee3b379..e88467262125ee4292ba44920b9d487305531963 100644
--- a/content/browser/loader/resource_loader_unittest.cc
+++ b/content/browser/loader/resource_loader_unittest.cc
@@ -4,21 +4,33 @@
 
 #include "content/browser/loader/resource_loader.h"
 
+#include "base/file_util.h"
+#include "base/files/file.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/platform_file.h"
 #include "base/run_loop.h"
 #include "content/browser/browser_thread_impl.h"
+#include "content/browser/loader/redirect_to_file_resource_handler.h"
 #include "content/browser/loader/resource_loader_delegate.h"
 #include "content/public/browser/resource_request_info.h"
+#include "content/public/common/resource_response.h"
 #include "content/public/test/mock_resource_context.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "content/test/test_content_browser_client.h"
 #include "ipc/ipc_message.h"
+#include "net/base/mock_file_stream.h"
 #include "net/base/request_priority.h"
 #include "net/cert/x509_certificate.h"
 #include "net/ssl/client_cert_store.h"
 #include "net/ssl/ssl_cert_request_info.h"
 #include "net/url_request/url_request.h"
+#include "net/url_request/url_request_job_factory_impl.h"
+#include "net/url_request/url_request_test_job.h"
 #include "net/url_request/url_request_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "webkit/common/blob/shareable_file_reference.h"
+
+using webkit_blob::ShareableFileReference;
 
 namespace content {
 namespace {
@@ -69,11 +81,32 @@ class ClientCertStoreStub : public net::ClientCertStore {
 // initialize ResourceLoader.
 class ResourceHandlerStub : public ResourceHandler {
  public:
-  ResourceHandlerStub() : ResourceHandler(NULL) {}
+  explicit ResourceHandlerStub(net::URLRequest* request)
+      : ResourceHandler(request),
+        defer_start_(false),
+        received_response_completed_(false),
+        total_bytes_downloaded_(0) {
+  }
+
+  void set_defer_start(bool defer_start) { defer_start_ = defer_start; }
+
+  const GURL& start_url() const { return start_url_; }
+  ResourceResponse* response() const { return response_.get(); }
+  bool received_response_completed() const {
+    return received_response_completed_;
+  }
+  const net::URLRequestStatus& status() const { return status_; }
+  int total_bytes_downloaded() const { return total_bytes_downloaded_; }
 
+  void Resume() {
+    controller()->Resume();
+  }
+
+  // ResourceHandler implementation:
   virtual bool OnUploadProgress(int request_id,
                                 uint64 position,
                                 uint64 size) OVERRIDE {
+    NOTREACHED();
     return true;
   }
 
@@ -81,16 +114,24 @@ class ResourceHandlerStub : public ResourceHandler {
                                    const GURL& url,
                                    ResourceResponse* response,
                                    bool* defer) OVERRIDE {
+    NOTREACHED();
     return true;
   }
 
   virtual bool OnResponseStarted(int request_id,
                                  ResourceResponse* response,
-                                 bool* defer) OVERRIDE { return true; }
+                                 bool* defer) OVERRIDE {
+    EXPECT_FALSE(response_);
+    response_ = response;
+    return true;
+  }
 
   virtual bool OnWillStart(int request_id,
                            const GURL& url,
                            bool* defer) OVERRIDE {
+    EXPECT_TRUE(start_url_.is_empty());
+    start_url_ = url;
+    *defer = defer_start_;
     return true;
   }
 
@@ -104,23 +145,40 @@ class ResourceHandlerStub : public ResourceHandler {
                           scoped_refptr<net::IOBuffer>* buf,
                           int* buf_size,
                           int min_size) OVERRIDE {
-    return true;
+    NOTREACHED();
+    return false;
   }
 
   virtual bool OnReadCompleted(int request_id,
                                int bytes_read,
                                bool* defer) OVERRIDE {
-    return true;
+    NOTREACHED();
+    return false;
   }
 
   virtual void OnResponseCompleted(int request_id,
                                    const net::URLRequestStatus& status,
                                    const std::string& security_info,
                                    bool* defer) OVERRIDE {
+    // TODO(davidben): This DCHECK currently fires everywhere. Fix the places in
+    // ResourceLoader where OnResponseCompleted is signaled twice.
+    // DCHECK(!received_response_completed_);
+    received_response_completed_ = true;
+    status_ = status;
   }
 
   virtual void OnDataDownloaded(int request_id,
-                                int bytes_downloaded) OVERRIDE {}
+                                int bytes_downloaded) OVERRIDE {
+    total_bytes_downloaded_ += bytes_downloaded;
+  }
+
+ private:
+  bool defer_start_;
+  GURL start_url_;
+  scoped_refptr<ResourceResponse> response_;
+  bool received_response_completed_;
+  net::URLRequestStatus status_;
+  int total_bytes_downloaded_;
 };
 
 // Test browser client that captures calls to SelectClientCertificates and
@@ -169,6 +227,80 @@ class ResourceContextStub : public MockResourceContext {
   scoped_ptr<net::ClientCertStore> dummy_cert_store_;
 };
 
+// Fails to create a temporary file with the given error.
+void CreateTemporaryError(
+    base::File::Error error,
+    const CreateTemporaryFileStreamCallback& callback) {
+  scoped_ptr<net::FileStream> null_stream;
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(callback, error, base::Passed(&null_stream),

[mmenke, 2014/03/03 21:10:11]

Doesn't really matter, but can you just use "scoped_ptr<net::FileStream>()" and
get rid of null_stream?

[davidben, 2014/03/03 23:20:18]

Done. I thought that didn't work, but apparently you spell that
base::Passed(scoped_ptr<...>())

+                 scoped_refptr<ShareableFileReference>()));
+}
+
+// Glue code to mock up a RedirectToFileResourceHandler with a MockFileStream
+// and a pre-created temporary file.
+class RedirectToFileMock {
+ public:
+  RedirectToFileMock() {
+    base::FilePath file_path;
+    CHECK(base::CreateTemporaryFile(&file_path));
+    base::PlatformFile platform_file =
+        base::CreatePlatformFile(file_path,
+                                 base::PLATFORM_FILE_WRITE |
+                                 base::PLATFORM_FILE_TEMPORARY |
+                                 base::PLATFORM_FILE_CREATE_ALWAYS |
+                                 base::PLATFORM_FILE_ASYNC,
+                                 NULL, NULL);
+    CHECK_NE(base::kInvalidPlatformFileValue, platform_file);
+    file_stream_.reset(
+        new net::testing::MockFileStream(
+            platform_file,
+            base::PLATFORM_FILE_WRITE | base::PLATFORM_FILE_ASYNC,
+            NULL, base::MessageLoopProxy::current()));
+    deletable_file_ =
+        ShareableFileReference::GetOrCreate(
+            file_path,
+            ShareableFileReference::DELETE_ON_FINAL_RELEASE,
+            BrowserThread::GetMessageLoopProxyForThread(
+                BrowserThread::FILE).get());
+  }
+
+  net::testing::MockFileStream* file_stream() const {
+    return file_stream_.get();
+  }
+  ShareableFileReference* deletable_file() const {

[mmenke, 2014/03/03 21:10:11]

As-is, these only work before PostCallback is called.  I think that's a
non-obvious property.  Suggest a comment, as changing that property looks like a
bit of work.

[davidben, 2014/03/03 23:20:18]

Done.

+    return deletable_file_.get();
+  }
+
+  scoped_ptr<RedirectToFileResourceHandler> CreateResourceHandler(
+      scoped_ptr<ResourceHandler> next_handler,
+      net::URLRequest* request) {
+    scoped_ptr<RedirectToFileResourceHandler> handler(
+        new RedirectToFileResourceHandler(next_handler.Pass(), request));
+    handler->SetCreateTemporaryFileStreamFunctionForTesting(
+        base::Bind(&RedirectToFileMock::PostCallback,
+                   base::Unretained(this)));
+    return handler.Pass();
+  }
+
+ private:
+  void PostCallback(const CreateTemporaryFileStreamCallback& callback) {
+    DCHECK(file_stream_);
+    DCHECK(deletable_file_);

[mmenke, 2014/03/03 21:10:11]

Weird to mix CHECKs (Higher up in this CL) and DCHECKs in tests.  Fine with
either one (I tend to prefer CHECKs, since they're tests and it makes it clear
they run in release, others prefer DCHECKs, since they're still run on the
trybots, apparently, and they don't run in production code)

[davidben, 2014/03/03 23:20:18]

Done.

+    scoped_ptr<net::FileStream> file_stream =
+        file_stream_.PassAs<net::FileStream>();

[mmenke, 2014/03/03 21:10:11]

Can you just inline "file_stream_.PassAs<net::FileStream>()" in the call to
bind?  Or is the call to base::Passed still needed in that case?  If so, this is
probably prettier.

[davidben, 2014/03/03 23:20:18]

Done. base::Passed is still needed, but apparently it has a mode that doesn't
take an address. (Funny, I could have sworn that didn't work...)

+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(callback, base::File::FILE_OK,
+                   base::Passed(&file_stream), deletable_file_));
+    deletable_file_ = NULL;
+  }
+
+  scoped_ptr<net::testing::MockFileStream> file_stream_;
+  scoped_refptr<ShareableFileReference> deletable_file_;

[mmenke, 2014/03/03 21:10:11]

DISALLOW_COPY_AND_ASSIGN?  Not copyable anyways, with the scoped_ptr, but best
to be careful.

[davidben, 2014/03/03 23:20:18]

Done.

+};
+
 }  // namespace
 
 class ResourceLoaderTest : public testing::Test,
@@ -177,6 +309,26 @@ class ResourceLoaderTest : public testing::Test,
   ResourceLoaderTest()
     : thread_bundle_(content::TestBrowserThreadBundle::IO_MAINLOOP),
       resource_context_(&test_url_request_context_) {
+    job_factory_.SetProtocolHandler(
+        "test", net::URLRequestTestJob::CreateProtocolHandler());
+    test_url_request_context_.set_job_factory(&job_factory_);
+  }
+
+  scoped_ptr<net::URLRequest> CreateTestRequest(const GURL& url) {
+    const int kRenderProcessId = 1;
+    const int kRenderViewId = 2;
+
+    scoped_ptr<net::URLRequest> request(
+        new net::URLRequest(url, net::DEFAULT_PRIORITY, NULL,
+                            resource_context_.GetRequestContext()));
+    ResourceRequestInfo::AllocateForTesting(request.get(),
+                                            ResourceType::MAIN_FRAME,
+                                            &resource_context_,
+                                            kRenderProcessId,
+                                            kRenderViewId,
+                                            MSG_ROUTING_NONE,
+                                            false);
+    return request.Pass();
   }
 
   // ResourceLoaderDelegate:
@@ -197,6 +349,7 @@ class ResourceLoaderTest : public testing::Test,
 
   content::TestBrowserThreadBundle thread_bundle_;
 
+  net::URLRequestJobFactoryImpl job_factory_;
   net::TestURLRequestContext test_url_request_context_;
   ResourceContextStub resource_context_;
 };
@@ -206,21 +359,7 @@ class ResourceLoaderTest : public testing::Test,
 // certificates are correctly passed to the content browser client for
 // selection.
 TEST_F(ResourceLoaderTest, ClientCertStoreLookup) {
-  const int kRenderProcessId = 1;
-  const int kRenderViewId = 2;
-
-  scoped_ptr<net::URLRequest> request(
-      new net::URLRequest(GURL("dummy"),
-                          net::DEFAULT_PRIORITY,
-                          NULL,
-                          resource_context_.GetRequestContext()));
-  ResourceRequestInfo::AllocateForTesting(request.get(),
-                                          ResourceType::MAIN_FRAME,
-                                          &resource_context_,
-                                          kRenderProcessId,
-                                          kRenderViewId,
-                                          MSG_ROUTING_NONE,
-                                          false);
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(GURL("dummy"));
 
   // Set up the test client cert store.
   net::CertificateList dummy_certs(1, scoped_refptr<net::X509Certificate>(
@@ -237,7 +376,8 @@ TEST_F(ResourceLoaderTest, ClientCertStoreLookup) {
   resource_context_.SetClientCertStore(
       test_store.PassAs<net::ClientCertStore>());
 
-  scoped_ptr<ResourceHandler> resource_handler(new ResourceHandlerStub());
+  scoped_ptr<ResourceHandler> resource_handler(
+      new ResourceHandlerStub(request.get()));
   ResourceLoader loader(request.Pass(), resource_handler.Pass(), this);
 
   // Prepare a dummy certificate request.
@@ -272,27 +412,14 @@ TEST_F(ResourceLoaderTest, ClientCertStoreLookup) {
 // on a platform with a NULL client cert store still calls the content browser
 // client for selection.
 TEST_F(ResourceLoaderTest, ClientCertStoreNull) {
-  const int kRenderProcessId = 1;
-  const int kRenderViewId = 2;
-
-  scoped_ptr<net::URLRequest> request(
-      new net::URLRequest(GURL("dummy"),
-                          net::DEFAULT_PRIORITY,
-                          NULL,
-                          resource_context_.GetRequestContext()));
-  ResourceRequestInfo::AllocateForTesting(request.get(),
-                                          ResourceType::MAIN_FRAME,
-                                          &resource_context_,
-                                          kRenderProcessId,
-                                          kRenderViewId,
-                                          MSG_ROUTING_NONE,
-                                          false);
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(GURL("dummy"));
 
   // Ownership of the |request| is about to be turned over to ResourceLoader. We
   // need to keep a raw pointer copy to access this object later.
   net::URLRequest* raw_ptr_to_request = request.get();
 
-  scoped_ptr<ResourceHandler> resource_handler(new ResourceHandlerStub());
+  scoped_ptr<ResourceHandler> resource_handler(
+      new ResourceHandlerStub(request.get()));
   ResourceLoader loader(request.Pass(), resource_handler.Pass(), this);
 
   // Prepare a dummy certificate request.
@@ -319,4 +446,233 @@ TEST_F(ResourceLoaderTest, ClientCertStoreNull) {
   EXPECT_EQ(net::CertificateList(), test_client.passed_certs());
 }
 
+// Tests that a RedirectToFileResourceHandler works and forwards everything
+// downstream.
+TEST_F(ResourceLoaderTest, RedirectToFile) {
+  RedirectToFileMock redirect_to_file_mock;
+  base::FilePath temp_path = redirect_to_file_mock.deletable_file()->path();
+
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+  scoped_ptr<ResourceHandler> resource_handler(leaf_handler);
+  resource_handler = redirect_to_file_mock.CreateResourceHandler(
+      resource_handler.Pass(), request.get());
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.Pass(), this));
+
+  // Run it to completion.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // Check that the handler forwarded all information to the downstream handler.
+  EXPECT_EQ(temp_path, leaf_handler->response()->head.download_file_path);
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::SUCCESS, leaf_handler->status().status());
+  EXPECT_EQ(net::URLRequestTestJob::test_data_1().size(),
+            static_cast<size_t>(leaf_handler->total_bytes_downloaded()));
+
+  // Check that the data was written to the file.
+  std::string contents;
+  ASSERT_TRUE(base::ReadFileToString(temp_path, &contents));
+  EXPECT_EQ(net::URLRequestTestJob::test_data_1(), contents);
+
+  // Release the loader. The file should be gone now.
+  loader.reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_FALSE(base::PathExists(temp_path));
+}
+
+// Tests that RedirectToFileResourceHandler handles errors in creating the
+// temporary file.
+TEST_F(ResourceLoaderTest, RedirectToFileCreateTemporaryError) {
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+
+  scoped_ptr<RedirectToFileResourceHandler> resource_handler(
+      new RedirectToFileResourceHandler(
+          scoped_ptr<ResourceHandler>(leaf_handler), request.get()));
+  resource_handler->SetCreateTemporaryFileStreamFunctionForTesting(
+      base::Bind(&CreateTemporaryError, base::File::FILE_ERROR_FAILED));
+
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.PassAs<ResourceHandler>(), this));
+
+  // Run it to completion.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // To downstream, the request was canceled.
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::CANCELED, leaf_handler->status().status());
+  EXPECT_EQ(0, leaf_handler->total_bytes_downloaded());
+}
+
+// Tests that RedirectToFileResourceHandler handles synchronous write errors.
+TEST_F(ResourceLoaderTest, RedirectToFileWriteError) {
+  RedirectToFileMock redirect_to_file_mock;
+  base::FilePath temp_path = redirect_to_file_mock.deletable_file()->path();
+  net::testing::MockFileStream* mock_file_stream =
+      redirect_to_file_mock.file_stream();
+  mock_file_stream->set_forced_error(net::ERR_FAILED);
+
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+  scoped_ptr<ResourceHandler> resource_handler(leaf_handler);
+  resource_handler = redirect_to_file_mock.CreateResourceHandler(
+      resource_handler.Pass(), request.get());
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.Pass(), this));
+
+  // Run it to completion.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // To downstream, the request was canceled sometime after it started, but
+  // before any data was written.
+  EXPECT_EQ(temp_path, leaf_handler->response()->head.download_file_path);
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::CANCELED, leaf_handler->status().status());
+  EXPECT_EQ(0, leaf_handler->total_bytes_downloaded());

[mmenke, 2014/03/03 21:10:11]

Check that the file was deleted?  Without a real write failing, suppose it
doesn't really add much to the test, but still feels like we should be doing it
(Same goes for the next 3 tests as well).

[davidben, 2014/03/03 23:20:18]

Done.

+}
+
+// Tests that RedirectToFileResourceHandler handles asynchronous write errors.
+TEST_F(ResourceLoaderTest, RedirectToFileWriteErrorAsync) {
+  RedirectToFileMock redirect_to_file_mock;
+  base::FilePath temp_path = redirect_to_file_mock.deletable_file()->path();
+  net::testing::MockFileStream* mock_file_stream =
+      redirect_to_file_mock.file_stream();
+  mock_file_stream->set_forced_error_async(net::ERR_FAILED);
+
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+  scoped_ptr<ResourceHandler> resource_handler(leaf_handler);
+  resource_handler = redirect_to_file_mock.CreateResourceHandler(
+      resource_handler.Pass(), request.get());
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.Pass(), this));
+
+  // Run it to completion.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // To downstream, the request was canceled sometime after it started, but
+  // before any data was written.
+  EXPECT_EQ(temp_path, leaf_handler->response()->head.download_file_path);
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::CANCELED, leaf_handler->status().status());
+  EXPECT_EQ(0, leaf_handler->total_bytes_downloaded());
+}
+
+// Tests that RedirectToFileHandler defers completion if there are outstanding
+// writes and accounts for errors which occur in that time.
+TEST_F(ResourceLoaderTest, RedirectToFileDeferCompletion) {
+  // Program the MockFileStream to error asynchronously, but throttle the
+  // callback.
+  RedirectToFileMock redirect_to_file_mock;
+  base::FilePath temp_path = redirect_to_file_mock.deletable_file()->path();
+  net::testing::MockFileStream* mock_file_stream =
+      redirect_to_file_mock.file_stream();
+  mock_file_stream->set_forced_error_async(net::ERR_FAILED);
+  mock_file_stream->ThrottleCallbacks();
+
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  net::URLRequest* raw_ptr_to_request = request.get();
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+  scoped_ptr<ResourceHandler> resource_handler(leaf_handler);
+  resource_handler = redirect_to_file_mock.CreateResourceHandler(
+      resource_handler.Pass(), request.get());
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.Pass(), this));
+
+  // Run it as far as it will go.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // At this point, the request should have completed.
+  EXPECT_EQ(net::URLRequestStatus::SUCCESS,
+            raw_ptr_to_request->status().status());
+
+  // However, the resource loader stack is stuck somewhere after receiving the
+  // response.
+  EXPECT_EQ(temp_path, leaf_handler->response()->head.download_file_path);
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_FALSE(leaf_handler->received_response_completed());
+  EXPECT_EQ(0, leaf_handler->total_bytes_downloaded());
+
+  // Now, release the floodgates.
+  mock_file_stream->ReleaseCallbacks();
+  base::RunLoop().RunUntilIdle();
+
+  // Although the URLRequest was successful, the leaf handler sees a failure
+  // because the write never completed.
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::CANCELED, leaf_handler->status().status());
+}
+
+// Tests that a RedirectToFileResourceHandler behaves properly when the
+// downstream handler defers OnWillStart.
+TEST_F(ResourceLoaderTest, RedirectToFileDownstreamDeferStart) {
+  RedirectToFileMock redirect_to_file_mock;
+  base::FilePath temp_path =
+      redirect_to_file_mock.deletable_file()->path();
+
+  // Set up the request.
+  scoped_ptr<net::URLRequest> request = CreateTestRequest(
+      net::URLRequestTestJob::test_url_1());
+  ResourceHandlerStub* leaf_handler = new ResourceHandlerStub(request.get());
+  scoped_ptr<ResourceHandler> resource_handler(leaf_handler);
+  resource_handler = redirect_to_file_mock.CreateResourceHandler(
+      resource_handler.Pass(), request.get());
+  scoped_ptr<ResourceLoader> loader(new ResourceLoader(
+      request.Pass(), resource_handler.Pass(), this));
+
+  // Defer OnWillStart.
+  leaf_handler->set_defer_start(true);
+
+  // Run as far as we'll go.
+  loader->StartRequest();
+  base::RunLoop().RunUntilIdle();
+
+  // The request should have stopped at OnWillStart.
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_FALSE(leaf_handler->response());
+  EXPECT_FALSE(leaf_handler->received_response_completed());
+  EXPECT_EQ(0, leaf_handler->total_bytes_downloaded());
+
+  // Now resume the request. Now we complete.
+  leaf_handler->Resume();
+  base::RunLoop().RunUntilIdle();
+
+  // Check that the handler forwarded all information to the downstream handler.
+  EXPECT_EQ(temp_path, leaf_handler->response()->head.download_file_path);
+  EXPECT_EQ(net::URLRequestTestJob::test_url_1(), leaf_handler->start_url());
+  EXPECT_TRUE(leaf_handler->received_response_completed());
+  EXPECT_EQ(net::URLRequestStatus::SUCCESS, leaf_handler->status().status());
+  EXPECT_EQ(net::URLRequestTestJob::test_data_1().size(),
+            static_cast<size_t>(leaf_handler->total_bytes_downloaded()));
+
+  // Check that the data was written to the file.
+  std::string contents;
+  ASSERT_TRUE(base::ReadFileToString(temp_path, &contents));
+  EXPECT_EQ(net::URLRequestTestJob::test_data_1(), contents);
+
+  // Release the loader. The file should be gone now.
+  loader.reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_FALSE(base::PathExists(temp_path));
+}
+
 }  // namespace content