Fix flipped views on Mac

content/browser/compositor/browser_compositor_view_private_mac.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_VIEW_PRIVATE_MAC_H_
 #define CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_VIEW_PRIVATE_MAC_H_
 
 #include "content/browser/compositor/browser_compositor_view_mac.h"
 
 namespace content {
 class BrowserCompositorViewCocoaHelper;
 }
 
 // An NSView drawn by a ui::Compositor. This structure is expensive to create,
 // because it has a ui::Compositor. As a result, this structure may be recycled
 // across multiple BrowserCompositorViewMac objects.
 @interface BrowserCompositorViewCocoa : NSView {
   scoped_ptr<ui::Compositor> compositor_;
 
-  base::scoped_nsobject<CALayer> background_layer_;
+  // A flipped layer, which acts as the parent of the compositing and software
+  // layers. This layer is flipped so that the we don't need to recompute the
+  // origin for sub-layers when their position changes (this is impossible when
+  // using remote layers, as their size change cannot be synchronized with the
+  // window). This indirection is needed because flipping hosted layers (like
+  // |background_layer_| of RenderWidgetHostViewCocoa) leads to unpredictable
+  // behavior.
+  base::scoped_nsobject<CALayer> flipped_layer_;
+
   base::scoped_nsobject<CompositingIOSurfaceLayer> accelerated_layer_;
   int accelerated_layer_output_surface_id_;
   std::vector<ui::LatencyInfo> accelerated_latency_info_;
+
   base::scoped_nsobject<SoftwareLayer> software_layer_;
 
   content::BrowserCompositorViewMacClient* client_;
   scoped_ptr<content::BrowserCompositorViewCocoaHelper> helper_;
 }
 
 // Change the client and superview of the view. If this is set to NULL then
 // the compositor will be prepared to be recycled.
 - (void)setClient:(content::BrowserCompositorViewMacClient*)client;
 
@@ skipping 26 matching lines @@
  private:
   // CompositingIOSurfaceLayerClient implementation:
   virtual void AcceleratedLayerDidDrawFrame(bool succeeded) OVERRIDE;
 
   BrowserCompositorViewCocoa* view_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_COMPOSITOR_BROWSER_COMPOSITOR_VIEW_PRIVATE_MAC_H_