Rebind EGL context to flush driver caches.

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 522 matching lines @@
   extensions_ = JoinString(ext, " ");
 }
 
 bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
   bool switched_contexts = g_current_gl_context_tls->Get() != this;
   GLSurface* current_surface = GLSurface::GetCurrent();
   if (switched_contexts || surface != current_surface) {
     // MakeCurrent 'lite' path that avoids potentially expensive MakeCurrent()
     // calls if the GLSurface uses the same underlying surface or renders to
     // an FBO.
-    if (switched_contexts || !current_surface ||
+    if (switched_contexts || !current_surface || !surface ||

[ericrk, 2015/07/13 21:15:33]

This is a bit weird as IsCurrent(surface) always returns true if surface is
NULL, so we'd never null things (it downgrades to a check for the context being
current).

         !virtual_context->IsCurrent(surface)) {
       if (!real_context_->MakeCurrent(surface)) {
         return false;
       }
     }
   }
 
   bool state_dirtied_externally = real_context_->GetStateWasDirtiedExternally();
   real_context_->SetStateWasDirtiedExternally(false);
 
@@ skipping 20 matching lines @@
           (current_context_ && !state_dirtied_externally && !switched_contexts)
               ? current_context_->GetGLStateRestorer()
               : NULL);
     }
     SetGLApi(temp);
     current_context_ = virtual_context;
   }
   SetGLApi(this);
 
   virtual_context->SetCurrent(surface);
-  if (!surface->OnMakeCurrent(virtual_context)) {
+  if (surface && !surface->OnMakeCurrent(virtual_context)) {
     LOG(ERROR) << "Could not make GLSurface current.";
     return false;
   }
   return true;
 }
 
 void VirtualGLApi::OnReleaseVirtuallyCurrent(GLContext* virtual_context) {
   if (current_context_ == virtual_context)
     current_context_ = NULL;
 }
@@ skipping 18 matching lines @@
 ScopedSetGLToRealGLApi::ScopedSetGLToRealGLApi()
     : old_gl_api_(GetCurrentGLApi()) {
   SetGLToRealGLApi();
 }
 
 ScopedSetGLToRealGLApi::~ScopedSetGLToRealGLApi() {
   SetGLApi(old_gl_api_);
 }
 
 }  // namespace gfx