Make the top bar semitransparent when in immersive fullscreen

chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc

Index: chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc
diff --git a/chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc b/chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc
index bebb5eb84e715dc21dc7e2e8364a4c09500c9d66..06dea08c5947b012acc4d2e2606fdd8febf31c06 100644
--- a/chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc
+++ b/chrome/browser/ui/views/frame/immersive_mode_controller_ash.cc
@@ -168,6 +168,7 @@ bool ImmersiveModeControllerAsh::UpdateTabIndicators() {
 void ImmersiveModeControllerAsh::OnImmersiveRevealStarted() {
   visible_fraction_ = 0;
   browser_view_->top_container()->SetPaintToLayer(true);
+  browser_view_->top_container()->SetFillsBoundsOpaquely(false);

[James Cook, 2014/02/24 17:40:07]

So the top container for *all* immersive fullscreen reveals is now going to be
transparent?  Does that look OK for the typical browser window case with opaque
tabs?

[pkotwicz, 2014/02/27 19:26:51]

This merely disables some of the optimizations that we do if the contents of a
layer are fully opaque. This does not actually set the opacity of a layer.
Immersive reveals for browser windows will look exactly the same because because
we use fully opaque image assets to paint the top container.

   UpdateTabIndicators();
   LayoutBrowserRootView();
   FOR_EACH_OBSERVER(Observer, observers_, OnImmersiveRevealStarted());