Transfer theme & page background colors between changes of RWHV.

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 bb4128c8f0fda709aef73e59c5b2819c0d1bd7d6..a45a036393aeb5aa28aae63a3bdff73bd23d8788 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3910,6 +3910,15 @@ void WebContentsImpl::NotifyViewSwapped(RenderViewHost* old_host,
 
 void WebContentsImpl::NotifyFrameSwapped(RenderFrameHost* old_host,
                                          RenderFrameHost* new_host) {
+  // Pass the background color of the old host to the new one. This passes
+  // on the page background color of the old host (or the theme color if the
+  // page background color is not set). This avoids flashes of white when
+  // starting up new_host.
+  if (old_host && old_host->GetView() && new_host && new_host->GetView()) {
+    new_host->GetView()->SetBackgroundColor(
+        old_host->GetView()->background_color());

[no sievers, 2016/05/17 18:05:43]

You said this doesn't work reliably. Does it work better if you set the color
from RenderFrameHostManager::Navigate() where we call
delegate_->CreateRenderViewForRenderManager()?

The other way to make this a bit more robust would be to make the
background_color a property of the WebContentsView and then
WebContentsView::CreateViewForWidget() could set the right background color
immediately.

+  }
+
   FOR_EACH_OBSERVER(WebContentsObserver,
                     observers_,
                     RenderFrameHostChanged(old_host, new_host));