GPU: Keep track of the last real context and real surface made current.

ui/gl/gl_gl_api_implementation.cc

 // 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.
 
 #include "ui/gl/gl_gl_api_implementation.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 250 matching lines @@
       // an FBO.
       if (!surface->OnMakeCurrent(real_context_)) {
         LOG(ERROR) << "Could not make GLSurface current.";
         return false;
       }
     } else if (!real_context_->MakeCurrent(surface)) {
       return false;
     }
   }
 
-  DCHECK(GLSurface::GetCurrent());
-  DCHECK(real_context_->IsCurrent(GLSurface::GetCurrent()));
+  DCHECK_EQ(real_context_, GLContext::GetRealCurrent());
+  DCHECK(GLSurface::GetRealCurrent());
+  DCHECK(real_context_->IsCurrent(GLSurface::GetRealCurrent()));

[jonathan.backer, 2013/05/23 21:00:53]

Switching to a real surface is necessary because GLContextVirtual::IsCurrent is
permissive (as an optimization).

   DCHECK(virtual_context->IsCurrent(surface));
 
   if (switched_contexts || virtual_context != current_context_) {
     // There should be no errors from the previous context leaking into the
     // new context.
     DCHECK_EQ(glGetErrorFn(), static_cast<GLenum>(GL_NO_ERROR));
 
     current_context_ = virtual_context;
     // Set all state that is different from the real state
     // NOTE: !!! This is a temporary implementation that just restores all
     // state to let us test that it works.
     // TODO: ASAP, change this to something that only restores the state
     // needed for individual GL calls.
     GLApi* temp = GetCurrentGLApi();
     SetGLToRealGLApi();
     virtual_context->GetGLStateRestorer()->RestoreState();
     SetGLApi(temp);
   }
   SetGLApi(this);
+
   return true;
 }
 
 void VirtualGLApi::OnDestroyVirtualContext(GLContext* virtual_context) {
   if (current_context_ == virtual_context)
     current_context_ = NULL;
 }
 
 const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   switch (name) {
     case GL_EXTENSIONS:
       return reinterpret_cast<const GLubyte*>(extensions_.c_str());
     default:
       return driver_->fn.glGetStringFn(name);
   }
 }
 
 }  // namespace gfx