Make it possible for downstream projects to easily set the default fill color

content/browser/renderer_host/render_widget_host_view_aura.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/renderer_host/render_widget_host_view_aura.h"
 
 #include <set>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 476 matching lines @@
   bool overscroll_enabled = base::CommandLine::ForCurrentProcess()->
       GetSwitchValueASCII(switches::kOverscrollHistoryNavigation) != "0";
   SetOverscrollControllerEnabled(overscroll_enabled);
 
   selection_controller_client_.reset(
       new TouchSelectionControllerClientAura(this));
   CreateSelectionController();
 
   RenderViewHost* rvh = RenderViewHost::From(host_);
   if (rvh) {
-    // TODO(mostynb): actually use prefs.  Landing this as a separate CL
-    // first to rebaseline some unreliable layout tests.
-    ignore_result(rvh->GetWebkitPreferences());
+    WebPreferences prefs = rvh->GetWebkitPreferences();
+    background_color_ = prefs.default_background_color;
+    host_->SetBackgroundOpaque(GetBackgroundOpaque());

[chrishtr, 2016/07/29 18:15:41]

Why do you also need to set whether it's opaque? Isn't that set already?

   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewAura, RenderWidgetHostView implementation:
 
 bool RenderWidgetHostViewAura::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(RenderWidgetHostViewAura, message)
@@ skipping 2498 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content