Propagate view background color when changing visible web contents.

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index fe651faec5dc9c3ae045fc0ec60ce8e54dfcb9f8..67aab7d5d2669c82f814e264d091d292c9c73a22 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -995,6 +995,20 @@ void Browser::TabDeactivated(WebContents* contents) {
     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,
@@ -1851,6 +1865,7 @@ 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);