Propagate view background color when changing visible web contents.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 11172c31d3b9c4f0fc6bcffb7a69d687a4238cc9..67dd483b4cc7512db931237af3c65e8065bb580d 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3986,6 +3986,18 @@ void WebContentsImpl::NotifyViewSwapped(RenderViewHost* old_host,
 
 void WebContentsImpl::NotifyFrameSwapped(RenderFrameHost* old_host,
                                          RenderFrameHost* new_host) {
+  // 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.
+  if (old_host && new_host) {
+    RenderWidgetHostView* old_view = old_host->GetView();
+    RenderWidgetHostView* new_view = new_host->GetView();
+    if (old_view && new_view)
+      new_view->SetBackgroundColor(old_view->background_color());
+  }
+
   for (auto& observer : observers_)
     observer.RenderFrameHostChanged(old_host, new_host);
 }