CrOS: Don't paint tab-loading spinners in layers while in immersive fullscreen.

chrome/browser/ui/views/tabs/tab_strip.cc

 // Copyright (c) 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/views/tabs/tab_strip.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <iterator>
@@ skipping 1361 matching lines @@
       int x = previous_tab_bounds.right() - tab_bounds.x() -
           kStackedTabRightClip;
       clip->SetRect(x, 0, tab_bounds.width() - x, tab_bounds.height());
     }
   }
   return true;
 }
 
 bool TabStrip::CanPaintThrobberToLayer() const {
   // Disable layer-painting of throbbers if dragging, if any tab animation is in
-  // progress, or if stacked tabs are enabled.
+  // progress, or if stacked tabs are enabled. Also disable in fullscreen: when
+  // "immersive" the tab strip could be sliding in or out while transitioning to
+  // or away from |immersive_style_| and, for other modes, there's no tab strip.
   const bool dragging = drag_controller_ && drag_controller_->started_drag();
-  return !touch_layout_ && !dragging && !IsAnimating();
+  return !touch_layout_ && !dragging && !IsAnimating() &&
+         !GetWidget()->IsFullscreen();

[sky, 2016/03/03 20:31:01]

Are you sure you don't need a null check for GetWidget() here? I could easily
see this being triggered while there is no widget.

[tapted, 2016/03/03 22:44:07]

Added a null check - leaving it off certainly wasn't intentional. Thanks for
catching this! (And you're right - I couldn't find any protections e.g., in the
timer callback at BrowserView::LoadingAnimationCallback() where this is
triggered.)

 }
 
 bool TabStrip::IsIncognito() const {
   return controller()->IsIncognito();
 }
 
 bool TabStrip::IsImmersiveStyle() const {
   return immersive_style_;
 }
 
@@ skipping 1478 matching lines @@
           ConvertPointToViewAndGetEventHandler(this, newtab_button_, point);
       if (view)
         return view;
     }
     Tab* tab = FindTabForEvent(point);
     if (tab)
       return ConvertPointToViewAndGetEventHandler(this, tab, point);
   }
   return this;
 }