Revert of Mac Overlays: Add GPU back-pressure

ui/gl/gl_gl_api_implementation.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_GL_GL_API_IMPLEMENTATION_H_
 #define UI_GL_GL_GL_API_IMPLEMENTATION_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 18 matching lines @@
 void InitializeDynamicGLBindingsGL(GLContext* context);
 void InitializeDebugGLBindingsGL();
 void InitializeNullDrawGLBindingsGL();
 // TODO(danakj): Remove this when all test suites are using null-draw.
 bool HasInitializedNullDrawGLBindingsGL();
 bool SetNullDrawGLBindingsEnabledGL(bool enabled);
 void ClearGLBindingsGL();
 void SetGLToRealGLApi();
 void SetGLApi(GLApi* api);
 void SetGLApiToNoContext();
-GLApi* GetCurrentGLApi();
 const GLVersionInfo* GetGLVersionInfo();
 
 class GL_EXPORT GLApiBase : public GLApi {
  public:
   // Include the auto-generated part of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in
   // this file instead of having to edit some template or the code generator.
   #include "gl_bindings_api_autogen_gl.h"
 
  protected:
@@ skipping 83 matching lines @@
   // The real context we're running on.
   GLContext* real_context_;
 
   // The current virtual context.
   GLContext* current_context_;
 
   // The supported extensions being advertised for this virtual context.
   std::string extensions_;
 };
 
+class GL_EXPORT ScopedSetGLToRealGLApi {
+ public:
+  ScopedSetGLToRealGLApi();
+  ~ScopedSetGLToRealGLApi();
+
+ private:
+  GLApi* old_gl_api_;
+};
+
 }  // namespace gfx
 
 #endif  // UI_GL_GL_GL_API_IMPLEMENTATION_H_