Propagate view background color when changing visible web contents.

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 977 matching lines @@
   SearchTabHelper::FromWebContents(contents)->OnTabDeactivated();
 
   // Save what the user's currently typing, so it can be restored when we
   // switch back to this tab.
   window_->GetLocationBar()->SaveStateToContents(contents);
 
   if (instant_controller_)
     instant_controller_->TabDeactivated(contents);
 }
 
+// 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 navigating
+// from a site whith a dark background to another site with a dark background.
+void CopyBackgroundColor(WebContents* old_contents, WebContents* new_contents) {

[Peter Kasting, 2016/11/07 19:27:41]

Nit: I would inline this into the single caller as a newline-separated block,
with the comment above moved over as well.  Since this block is short and only
called once, to me this reads slightly more clearly than having to go look
elsewhere for the definition of this function.

[chrishtr, 2016/11/09 21:39:36]

Done.

+  if (old_contents && new_contents) {
+    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());
+  }
+}
+
 void Browser::ActiveTabChanged(WebContents* old_contents,
                                WebContents* new_contents,
                                int index,
                                int reason) {
   content::RecordAction(UserMetricsAction("ActiveTabChanged"));
 
   // Update the bookmark state, since the BrowserWindow may query it during
   // OnActiveTabChanged() below.
   UpdateBookmarkBarState(BOOKMARK_BAR_STATE_CHANGE_TAB_SWITCH);
 
@@ skipping 836 matching lines @@
   return size;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Browser, CoreTabHelperDelegate implementation:
 
 void Browser::SwapTabContents(content::WebContents* old_contents,
                               content::WebContents* new_contents,
                               bool did_start_load,
                               bool did_finish_load) {
+  CopyBackgroundColor(old_contents, new_contents);
   int index = tab_strip_model_->GetIndexOfWebContents(old_contents);
   DCHECK_NE(TabStripModel::kNoTab, index);
   tab_strip_model_->ReplaceWebContentsAt(index, new_contents);
 }
 
 bool Browser::CanReloadContents(content::WebContents* web_contents) const {
   return chrome::CanReload(this);
 }
 
 bool Browser::CanSaveContents(content::WebContents* web_contents) const {
@@ skipping 719 matching lines @@
   if (contents && !allow_js_access) {
     contents->web_contents()->GetController().LoadURL(
         target_url,
         content::Referrer(),
         ui::PAGE_TRANSITION_LINK,
         std::string());  // No extra headers.
   }
 
   return contents != NULL;
 }