Vend common GL context

ui/gfx/compositor/compositor_gl.h

Index: ui/gfx/compositor/compositor_gl.h
diff --git a/ui/gfx/compositor/compositor_gl.h b/ui/gfx/compositor/compositor_gl.h
index 0872d1ece0dda8042b6236c71244b570f823a0c0..cfa4756738bff30773e9a3082595b8b6de694442 100644
--- a/ui/gfx/compositor/compositor_gl.h
+++ b/ui/gfx/compositor/compositor_gl.h
@@ -8,6 +8,8 @@
 
 #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/size.h"
 
@@ -22,9 +24,48 @@ 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 SharedResources {
+ public:
+  static SharedResources* GetInstance();
+
+  bool MakeSharedContextCurrent();
+
+  // Creates a context that shares the resources hosted by this singleton.
+  scoped_refptr<gfx::GLContext> CreateContext(gfx::GLSurface* surface);
+
+  ui::TextureProgramGL* program_no_swizzle() {
+    return program_no_swizzle_.get();
+  }
+
+  ui::TextureProgramGL* program_swizzle() {
+    return program_swizzle_.get();
+  }
+
+ private:
+  friend struct DefaultSingletonTraits<SharedResources>;
+
+  SharedResources();
+  virtual ~SharedResources();
+
+  bool Initialize();
+  void Destroy();
+
+  bool initialized_;
+
+  scoped_refptr<gfx::GLContext> context_;
+  scoped_refptr<gfx::GLSurface> surface_;
+
+  scoped_ptr<ui::TextureProgramGL> program_swizzle_;
+  scoped_ptr<ui::TextureProgramGL> program_no_swizzle_;
+
+  DISALLOW_COPY_AND_ASSIGN(SharedResources);
+};
+
 class COMPOSITOR_EXPORT TextureGL : public Texture {
  public:
-  explicit TextureGL(CompositorGL* compositor);
+  TextureGL();
 
   virtual void SetCanvas(const SkCanvas& canvas,
                          const gfx::Point& origin,
@@ -39,7 +80,7 @@ class COMPOSITOR_EXPORT TextureGL : public Texture {
                     const gfx::Rect& clip_bounds_in_texture) OVERRIDE;
 
  protected:
-  TextureGL(CompositorGL* compositor, const gfx::Size& size);
+  explicit TextureGL(const gfx::Size& size);
   virtual ~TextureGL();
 
   // Actually draws the texture.
@@ -50,7 +91,6 @@ class COMPOSITOR_EXPORT TextureGL : public Texture {
 
   unsigned int texture_id_;
   gfx::Size size_;
-  CompositorGL* compositor_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TextureGL);
@@ -64,8 +104,8 @@ class COMPOSITOR_EXPORT CompositorGL : public Compositor {
   void MakeCurrent();
   gfx::Size GetSize();
 
-  TextureProgramGL* program_no_swizzle();
-  TextureProgramGL* program_swizzle();
+ protected:
+  virtual void OnWidgetSizeChanged() OVERRIDE;
 
  private:
   // Overridden from Compositor.
@@ -74,14 +114,11 @@ class COMPOSITOR_EXPORT CompositorGL : public Compositor {
   virtual void NotifyEnd() OVERRIDE;
   virtual void Blur(const gfx::Rect& bounds) OVERRIDE;
   virtual void SchedulePaint() OVERRIDE;
-  virtual void OnWidgetSizeChanged(const gfx::Size& size) OVERRIDE;
 
   // The GL context used for compositing.
   scoped_refptr<gfx::GLSurface> gl_surface_;
   scoped_refptr<gfx::GLContext> gl_context_;
 
-  gfx::Size size_;
-
   // Keep track of whether compositing has started or not.
   bool started_;