Update from chromium https://crrev.com/301315

ui/gl/gpu_switching_manager.h

 // 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.
 
 #ifndef UI_GL_GPU_SWITCHING_MANAGER_H_
 #define UI_GL_GPU_SWITCHING_MANAGER_H_
 
 #include <vector>
 
 #include "base/memory/singleton.h"
+#include "base/observer_list.h"
 #include "ui/gl/gl_export.h"
 #include "ui/gl/gpu_preference.h"
+#include "ui/gl/gpu_switching_observer.h"
 
 #if defined(OS_MACOSX)
 #include <OpenGL/OpenGL.h>
 #endif  // OS_MACOSX
 
 namespace ui {
 
 class GL_EXPORT GpuSwitchingManager {
  public:
   // Getter for the singleton. This will return NULL on failure.
@@ skipping 10 matching lines @@
   gfx::GpuPreference AdjustGpuPreference(gfx::GpuPreference gpu_preference);
 
   // In the browser process, the value for this flag is computed the first time
   // this function is called.
   // In the GPU process, the value is passed from the browser process using the
   // --supports-dual-gpus commandline switch.
   bool SupportsDualGpus();
 
   void SetGpuCount(size_t gpu_count);
 
+  void AddObserver(GpuSwitchingObserver* observer);
+  void RemoveObserver(GpuSwitchingObserver* observer);
+
+  // Called when a GPU switch is noticed by the system. In the browser process
+  // this is occurs as a result of a system observer. In the GPU process, this
+  // occurs as a result of an IPC from the browser. The system observer is kept
+  // in the browser process only so that any workarounds or blacklisting can
+  // be applied there.
+  void NotifyGpuSwitched();
+
  private:
   friend struct DefaultSingletonTraits<GpuSwitchingManager>;
 
   GpuSwitchingManager();
   virtual ~GpuSwitchingManager();
 
 #if defined(OS_MACOSX)
   void SwitchToDiscreteGpuMac();
 
   CGLPixelFormatObj discrete_pixel_format_;
 #endif  // OS_MACOSX
 
   gfx::GpuPreference gpu_switching_option_;
   bool gpu_switching_option_set_;
 
   bool supports_dual_gpus_;
   bool supports_dual_gpus_set_;
 
   size_t gpu_count_;
 
+  ObserverList<GpuSwitchingObserver> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(GpuSwitchingManager);
 };
 
 }  // namespace ui
 
 #endif  // UI_GL_GPU_SWITCHING_MANAGER_H_