Mac: Use Mavericks occlusion APIs for power savings.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 
@@ skipping 775 matching lines @@
       0);
   render_widget_host_->WasShown(renderer_latency_info);
 
   // If there is not a frame being currently drawn, kick one, so that the below
   // pause will have a frame to wait on.
   render_widget_host_->ScheduleComposite();
   PauseForPendingResizeOrRepaintsAndDraw();
 }
 
 void RenderWidgetHostViewMac::WasHidden() {
-  if (render_widget_host_->is_hidden())
-    return;
-
-  DestroyBrowserCompositorView();
+  // We want to call DestroyBrowserCompositorView on inactive tabs, but not on
+  // an active tab that is being occluded.
+  if (![cocoa_view_ window])
+    DestroyBrowserCompositorView();
 
   // If we have a renderer, then inform it that we are being hidden so it can
   // reduce its resource utilization.
-  render_widget_host_->WasHidden();
+  if (!render_widget_host_->is_hidden())
+    render_widget_host_->WasHidden();
 }
 
 void RenderWidgetHostViewMac::SetSize(const gfx::Size& size) {
   gfx::Rect rect = GetViewBounds();
   rect.set_size(size);
   SetBounds(rect);
 }
 
 void RenderWidgetHostViewMac::SetBounds(const gfx::Rect& rect) {
   // |rect.size()| is view coordinates, |rect.origin| is screen coordinates,
@@ skipping 2494 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end