Fix gl context change on dropping a texture

ui/gfx/compositor/compositor_gl.h

 // Copyright (c) 2011 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_GFX_COMPOSITOR_COMPOSITOR_GL_H_
 #define UI_GFX_COMPOSITOR_COMPOSITOR_GL_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/memory/ref_counted.h"
 #include "ui/gfx/compositor/compositor.h"
+#include "ui/gfx/gl/scoped_make_current.h"
 #include "ui/gfx/size.h"
 
 namespace gfx {
 class GLContext;
 class GLSurface;
 class Rect;
 }
 
 namespace ui {
 
 class CompositorGL;
 class TextureProgramGL;
 
 // We share resources (such as shaders) between different Compositors via
 // GLContext sharing so that we only have to create/destroy them once.
 class COMPOSITOR_EXPORT SharedResourcesGL : public SharedResources {
  public:
   static SharedResourcesGL* GetInstance();
 
   virtual bool MakeSharedContextCurrent();

[jonathan.backer, 2011/11/02 23:09:34]

I think that we can deprecate this in favour of the new method below. Maybe file
a bug and address as a separate CL.

 
+  // Creates an instance of ScopedMakeCurrent.
+  // Note: Caller is responsible for managing lifetime of returned pointer.
+  gfx::ScopedMakeCurrent* GetScopedMakeCurrent();
+
   // Creates a context that shares the resources hosted by this singleton.
   scoped_refptr<gfx::GLContext> CreateContext(gfx::GLSurface* surface);
 
   virtual void* GetDisplay();
 
   ui::TextureProgramGL* program_no_swizzle() {
     return program_no_swizzle_.get();
   }
 
   ui::TextureProgramGL* program_swizzle() {
@@ skipping 74 matching lines @@
 
   // Keep track of whether compositing has started or not.
   bool started_;
 
   DISALLOW_COPY_AND_ASSIGN(CompositorGL);
 };
 
 }  // namespace ui
 
 #endif  // UI_GFX_COMPOSITOR_COMPOSITOR_GL_H_