Ensure real GL Api is set before making GL calls.

ui/gl/gl_context_cgl.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_context_cgl.h"
 
 #include <OpenGL/CGLRenderers.h>
 #include <OpenGL/CGLTypes.h>
 #include <vector>
 
@@ skipping 168 matching lines @@
     return true;
 
   TRACE_EVENT0("gpu", "GLContextCGL::MakeCurrent");
 
   if (CGLSetCurrentContext(
       static_cast<CGLContextObj>(context_)) != kCGLNoError) {
     LOG(ERROR) << "Unable to make gl context current.";
     return false;
   }
 
+  // Set this as soon as the context is current, since we might call into GL.
+  SetRealGLApi();

[greggman, 2013/06/12 22:17:18]

Do you want to restore it if it fails?

I know that's a lot of refactoring but it seems like if it fails at line 193 or
like 198 then the previous RealGLApi should still be restored

Either that or it should be set to NULL so that if anyone is not checking the
results from MakeCurrent they'll fail rather than trashing someone else's
context.

What do you think?

+
   SetCurrent(surface);
   if (!InitializeExtensionBindings()) {
     ReleaseCurrent(surface);
     return false;
   }
 
   if (!surface->OnMakeCurrent(this)) {
     LOG(ERROR) << "Unable to make gl context current.";
     return false;
   }
 
-  SetRealGLApi();
   return true;
 }
 
 void GLContextCGL::ReleaseCurrent(GLSurface* surface) {
   if (!IsCurrent(surface))
     return;
 
   SetCurrent(NULL);
   CGLSetCurrentContext(NULL);
 }
@@ skipping 82 matching lines @@
 
 GLContextCGL::~GLContextCGL() {
   Destroy();
 }
 
 GpuPreference GLContextCGL::GetGpuPreference() {
   return gpu_preference_;
 }
 
 }  // namespace gfx