mac: Don't transfer background color to new tabs

chrome/browser/ui/browser.cc

 // Copyright 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 "chrome/browser/ui/browser.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 1017 matching lines @@
   window_->GetLocationBar()->SaveStateToContents(contents);
 
   if (instant_controller_)
     instant_controller_->TabDeactivated(contents);
 }
 
 void Browser::ActiveTabChanged(WebContents* old_contents,
                                WebContents* new_contents,
                                int index,
                                int reason) {
+// Mac correctly sets the initial background color of new tabs to the theme
+// background color, so it does not need this block of code. Aura should
+// implement this as well.
+// https://crbug.com/719230
+#if !defined(OS_MACOSX)
   // Copies the background color from an old WebContents to a new one that
   // replaces it on the screen. This allows the new WebContents to use the
   // old one's background color as the starting background color, before having
   // loaded any contents. As a result, we avoid flashing white when moving to
   // a new tab. (There is also code in RenderFrameHostManager to do something
   // similar for intra-tab navigations.)
   if (old_contents && new_contents) {
     // While GetMainFrame() is guaranteed to return non-null, GetView() is not,
     // e.g. between WebContents creation and creation of the
     // RenderWidgetHostView.
     RenderWidgetHostView* old_view = old_contents->GetMainFrame()->GetView();
     RenderWidgetHostView* new_view = new_contents->GetMainFrame()->GetView();
     if (old_view && new_view)
       new_view->SetBackgroundColor(old_view->background_color());
   }
+#endif
 
   base::RecordAction(UserMetricsAction("ActiveTabChanged"));
 
   // Update the bookmark state, since the BrowserWindow may query it during
   // OnActiveTabChanged() below.
   UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_TAB_SWITCH);
 
   // Let the BrowserWindow do its handling.  On e.g. views this changes the
   // focused object, which should happen before we update the toolbar below,
   // since the omnibox expects the correct element to already be focused when it
@@ skipping 1565 matching lines @@
     // new window later, thus we need to navigate the window now.
     if (contents) {
       contents->web_contents()->GetController().LoadURL(
           target_url, content::Referrer(), ui::PAGE_TRANSITION_LINK,
           std::string());  // No extra headers.
     }
   }
 
   return contents != NULL;
 }