During virtual context switches only restore texture units that have changed from the previous cont…

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 287 matching lines @@
 
   DCHECK_EQ(real_context_, GLContext::GetRealCurrent());
   DCHECK(real_context_->IsCurrent(NULL));
   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();
-    if (virtual_context->GetGLStateRestorer()->IsInitialized())
-      virtual_context->GetGLStateRestorer()->RestoreState();
+    if (virtual_context->GetGLStateRestorer()->IsInitialized()) {
+      virtual_context->GetGLStateRestorer()->RestoreState(
+          (current_context_)

[Sami, 2013/12/18 16:04:07]

It might be worth checking how often we go from MakeCurrent(NULL) =>
MakeCurrent(some_context) since that would defeat this optimization. I'm not
sure if that ever happens with virtual contexts though.

[kaanb, 2013/12/18 17:24:55]

I see MakeCurrent(NULL) -> MakeCurrent(some_context) transition a few times when
I first open a tab but not afterwards. 

+              ? current_context_->GetGLStateRestorer()->GetContextState()
+              : NULL);
+    }
     SetGLApi(temp);
+    current_context_ = virtual_context;
   }
   SetGLApi(this);
 
   virtual_context->SetCurrent(surface);
   if (!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;
 }
 
 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