aw: Update background colour on newly created main frames.

Bug: 802172
Change-Id: I5841fe34ee7226611a5ad2c66cf3c971fd40c670
Reviewed-on: https://chromium-review.googlesource.com/873977
Commit-Queue: Tobias Sargeant <tobiasjs@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530540}

android_webview/browser/renderer_host/aw_render_view_host_ext.cc

@@ -129,12 +129,6 @@ void AwRenderViewHostExt::SmoothScroll(int target_x,
       static_cast<int>(duration_ms)));
 }
 
-void AwRenderViewHostExt::RenderViewCreated(
-    content::RenderViewHost* render_view_host) {
-  web_contents()->GetMainFrame()->Send(new AwViewMsg_SetBackgroundColor(
-      web_contents()->GetMainFrame()->GetRoutingID(), background_color_));
-}
-
 void AwRenderViewHostExt::RenderViewHostChanged(
     content::RenderViewHost* old_host,
     content::RenderViewHost* new_host) {
@@ -154,6 +148,10 @@ void AwRenderViewHostExt::RenderFrameCreated(
   registry_.AddInterface(
       base::Bind(&web_restrictions::WebRestrictionsMojoImplementation::Create,
                  AwBrowserContext::GetDefault()->GetWebRestrictionProvider()));
+  if (!frame_host->GetParent()) {
+    frame_host->Send(new AwViewMsg_SetBackgroundColor(
+        frame_host->GetRoutingID(), background_color_));
+  }
 }
 
 void AwRenderViewHostExt::DidFinishNavigation(

android_webview/browser/renderer_host/aw_render_view_host_ext.h

@@ -81,7 +81,6 @@ class AwRenderViewHostExt : public content::WebContentsObserver {
 
  private:
   // content::WebContentsObserver implementation.
-  void RenderViewCreated(content::RenderViewHost* view_host) override;
   void RenderViewHostChanged(content::RenderViewHost* old_host,
                              content::RenderViewHost* new_host) override;
   void RenderFrameCreated(content::RenderFrameHost* frame_host) override;