Get renderer compositor message loop override dynamically

UI MessageLoop has not started when AwContentRedererClient is first
constructed. So pass in a getter function instead. This still does not
*guarantee* message loop will be constructed by the time Override is
called, but it should be ok since it *should* only be called in the
renderer. Add a DCHECK for null anyway.

R=joth@chromium.org
Android only change, ran through android bots.
NOTRY=true
BUG=179436


Review URL: https://chromiumcodereview.appspot.com/12639002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@186882 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 23 insertions, 15 deletions

diff --git a/android_webview/lib/main/aw_main_delegate.cc b/android_webview/lib/main/aw_main_delegate.cc
index 99a4b0d..4768c19 100644
--- a/android_webview/lib/main/aw_main_delegate.cc
+++ b/android_webview/lib/main/aw_main_delegate.cc
@@ -75,19 +75,24 @@ content::ContentBrowserClient*
   return content_browser_client_.get();
 }
 
-content::ContentRendererClient*
-    AwMainDelegate::CreateContentRendererClient() {
-  MessageLoop* renderer_compositor_loop = NULL;
-
+namespace {
+MessageLoop* GetRendererCompositorThreadOverrideLoop() {
   CommandLine* command_line = CommandLine::ForCurrentProcess();
-  if (command_line->HasSwitch(switches::kMergeUIAndRendererCompositorThreads)) {
-    renderer_compositor_loop =
-        content::BrowserThread::UnsafeGetMessageLoopForThread(
-            content::BrowserThread::UI);
-  }
+  if (!command_line->HasSwitch(
+      switches::kMergeUIAndRendererCompositorThreads))
+    return NULL;
+
+  MessageLoop* rv = content::BrowserThread::UnsafeGetMessageLoopForThread(
+      content::BrowserThread::UI);
+  DCHECK(rv);
+  return rv;
+}
+}
 
+content::ContentRendererClient*
+    AwMainDelegate::CreateContentRendererClient() {
   content_renderer_client_.reset(
-      new AwContentRendererClient(renderer_compositor_loop));
+      new AwContentRendererClient(&GetRendererCompositorThreadOverrideLoop));
   return content_renderer_client_.get();
 }
 
diff --git a/android_webview/renderer/aw_content_renderer_client.cc b/android_webview/renderer/aw_content_renderer_client.cc
index b0abcd0..14db191 100644
--- a/android_webview/renderer/aw_content_renderer_client.cc
+++ b/android_webview/renderer/aw_content_renderer_client.cc
@@ -22,8 +22,8 @@
 namespace android_webview {
 
 AwContentRendererClient::AwContentRendererClient(
-    MessageLoop* compositor_message_loop)
-    : compositor_message_loop_(compositor_message_loop) {
+    CompositorMessageLoopGetter* compositor_message_loop_getter)
+    : compositor_message_loop_getter_(compositor_message_loop_getter) {
 }
 
 AwContentRendererClient::~AwContentRendererClient() {
@@ -97,7 +97,7 @@ void AwContentRendererClient::PrefetchHostName(const char* hostname,
 }
 
 MessageLoop* AwContentRendererClient::OverrideCompositorMessageLoop() const {
-  return compositor_message_loop_;
+  return (*compositor_message_loop_getter_)();
 }
 
 }  // namespace android_webview
diff --git a/android_webview/renderer/aw_content_renderer_client.h b/android_webview/renderer/aw_content_renderer_client.h
index 72112c2..2df9141 100644
--- a/android_webview/renderer/aw_content_renderer_client.h
+++ b/android_webview/renderer/aw_content_renderer_client.h
@@ -18,7 +18,10 @@ namespace android_webview {
 
 class AwContentRendererClient : public content::ContentRendererClient {
  public:
-  explicit AwContentRendererClient(MessageLoop* compositor_message_loop);
+  typedef MessageLoop* CompositorMessageLoopGetter();
+
+  explicit AwContentRendererClient(
+      CompositorMessageLoopGetter* compositor_message_loop_getter);
   virtual ~AwContentRendererClient();
 
   // ContentRendererClient implementation.
@@ -41,7 +44,7 @@ class AwContentRendererClient : public content::ContentRendererClient {
  private:
   scoped_ptr<AwRenderProcessObserver> aw_render_process_observer_;
   scoped_ptr<components::VisitedLinkSlave> visited_link_slave_;
-  MessageLoop* compositor_message_loop_;
+  CompositorMessageLoopGetter* compositor_message_loop_getter_;
 };
 
 }  // namespace android_webview