Infrastructure for temportarily relinquishing GPU resources.

content/browser/gpu/gpu_process_host.h

Index: content/browser/gpu/gpu_process_host.h
diff --git a/content/browser/gpu/gpu_process_host.h b/content/browser/gpu/gpu_process_host.h
index 2952d3869effc927437dad452f2b05e214952caa..03dfb1afdbabd21ed6f95836c69db6277c174d6b 100644
--- a/content/browser/gpu/gpu_process_host.h
+++ b/content/browser/gpu/gpu_process_host.h
@@ -64,6 +64,8 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
   typedef base::Callback<void(const gfx::GpuMemoryBufferHandle& handle)>
       CreateGpuMemoryBufferCallback;
 
+  typedef base::Callback<void(bool successful)> RelinquishCallback;
+
   static bool gpu_enabled() { return gpu_enabled_; }
   static int gpu_crash_count() { return gpu_crash_count_; }
 
@@ -89,6 +91,10 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
   CONTENT_EXPORT static void RegisterGpuMainThreadFactory(
       GpuMainThreadFactoryFunction create);
 
+  // Relinquish all internal GPU driver resources. All windows should be closed
+  // and the browser is being set to be placed in the bacckground.
+  static void RelinquishResources(const RelinquishCallback& callback);
+
   // Get the GPU process host for the GPU process with the given ID. Returns
   // null if the process no longer exists.
   static GpuProcessHost* FromID(int host_id);
@@ -176,6 +182,8 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
 #if defined(OS_MACOSX)
   void OnAcceleratedSurfaceBuffersSwapped(const IPC::Message& message);
 #endif
+  void RelinquishResourcesInternal(const RelinquishCallback& callback);
+  void OnResourcesRelinquished(bool success);
 
   void CreateChannelCache(int32 client_id);
   void OnDestroyChannel(int32 client_id);
@@ -230,6 +238,9 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
   // Time Init started.  Used to log total GPU process startup time to UMA.
   base::TimeTicks init_start_time_;
 
+  // Completion callback for RelinquishResources.
+  RelinquishCallback relinquish_callback_;
+
   // Whether this host recorded a GPU crash or not.
   bool gpu_crash_recorded_;