gpu: Bind dummy GL API when no context is current

ui/gl/gl_context.h

Index: ui/gl/gl_context.h
diff --git a/ui/gl/gl_context.h b/ui/gl/gl_context.h
index f40b1bba78647ab9ef7090ffa420e4c5ba1b739c..2f05e1b98fd6b597a96f140fa65ae9cceafe7aef 100644
--- a/ui/gl/gl_context.h
+++ b/ui/gl/gl_context.h
@@ -117,6 +117,20 @@ class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
  protected:
   virtual ~GLContext();
 
+  // Will release the given context and surface  when going out of scope,
+  // unless Release() is called.
+  class ScopedReleaseCurrent {
+   public:
+    ScopedReleaseCurrent(GLContext* context, GLSurface* surface);
+    ~ScopedReleaseCurrent();
+
+    void Release();
+
+   private:
+    GLContext* context_;

[piman, 2014/04/01 23:00:02]

nit: scoped_refptr? (below too)

+    GLSurface* surface_;
+  };
+
   // Sets the GL api to the real hardware API (vs the VirtualAPI)
   static void SetRealGLApi();
   virtual void SetCurrent(GLSurface* surface);