content: Post WebUrlLoader tasks through the RendererScheduler::DefaultTaskRunner.

This CL routes calls to PostTask in WebUrlLoader through the DefaultTaskRunner
of the RendererScheduler, rather than directly posting to the message loop.
This avoids a bug in http/tests/loading/simple-subframe.html where
didCommitProvisionalLoadd (for an iframe) and didFinishDocumentLoad (for the
main frame) could be reordered.  It also ensures that these tasks are
properly scheduled with respect to the other tasks in the system.

BUG=432129

Review URL: https://codereview.chromium.org/727763004

Cr-Commit-Position: refs/heads/master@{#304413}

1 files changed, 16 insertions, 8 deletions

diff --git a/content/child/web_url_loader_impl.cc b/content/child/web_url_loader_impl.cc
index 9468b43..bd6fe10 100644
--- a/content/child/web_url_loader_impl.cc
+++ b/content/child/web_url_loader_impl.cc
@@ -13,7 +13,7 @@
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/message_loop/message_loop.h"
+#include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "content/child/ftp_directory_listing_response_delegate.h"
@@ -294,7 +294,9 @@ RequestContextType GetRequestContextType(const WebURLRequest& request) {
 class WebURLLoaderImpl::Context : public base::RefCounted<Context>,
                                   public RequestPeer {
  public:
-  Context(WebURLLoaderImpl* loader, ResourceDispatcher* resource_dispatcher);
+  Context(WebURLLoaderImpl* loader,
+          ResourceDispatcher* resource_dispatcher,
+          scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
   WebURLLoaderClient* client() const { return client_; }
   void set_client(WebURLLoaderClient* client) { client_ = client; }
@@ -339,6 +341,7 @@ class WebURLLoaderImpl::Context : public base::RefCounted<Context>,
   WebURLRequest request_;
   WebURLLoaderClient* client_;
   ResourceDispatcher* resource_dispatcher_;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   WebReferrerPolicy referrer_policy_;
   scoped_ptr<ResourceLoaderBridge> bridge_;
   scoped_ptr<FtpDirectoryListingResponseDelegate> ftp_listing_delegate_;
@@ -353,11 +356,14 @@ class WebURLLoaderImpl::Context : public base::RefCounted<Context>,
   bool got_all_stream_body_data_;
 };
 
-WebURLLoaderImpl::Context::Context(WebURLLoaderImpl* loader,
-                                   ResourceDispatcher* resource_dispatcher)
+WebURLLoaderImpl::Context::Context(
+    WebURLLoaderImpl* loader,
+    ResourceDispatcher* resource_dispatcher,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : loader_(loader),
       client_(NULL),
       resource_dispatcher_(resource_dispatcher),
+      task_runner_(task_runner),
       referrer_policy_(blink::WebReferrerPolicyDefault),
       got_all_stream_body_data_(false) {
 }
@@ -434,8 +440,8 @@ void WebURLLoaderImpl::Context::Start(const WebURLRequest& request,
           GetInfoFromDataURL(sync_load_response->url, sync_load_response,
                              &sync_load_response->data);
     } else {
-      base::MessageLoop::current()->PostTask(
-          FROM_HERE, base::Bind(&Context::HandleDataURL, this));
+      task_runner_->PostTask(FROM_HERE,
+                             base::Bind(&Context::HandleDataURL, this));
     }
     return;
   }
@@ -952,8 +958,10 @@ void WebURLLoaderImpl::Context::OnHandleGotWritable(MojoResult result) {
 
 // WebURLLoaderImpl -----------------------------------------------------------
 
-WebURLLoaderImpl::WebURLLoaderImpl(ResourceDispatcher* resource_dispatcher)
-    : context_(new Context(this, resource_dispatcher)) {
+WebURLLoaderImpl::WebURLLoaderImpl(
+    ResourceDispatcher* resource_dispatcher,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : context_(new Context(this, resource_dispatcher, task_runner)) {
 }
 
 WebURLLoaderImpl::~WebURLLoaderImpl() {