Use webGL context creation attribute to activate GLSL validation

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.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 "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 138 matching lines @@
     return false;
 
   TRACE_EVENT0("gpu", "WebGfxCtx3DCmdBfrImpl::MaybeInitializeGL");
 
   if (!CreateContext(surface_id_ != 0)) {
     Destroy();
     initialize_failed_ = true;
     return false;
   }
 
-  // TODO(twiz):  This code is too fragile in that it assumes that only WebGL
-  // contexts will request noExtensions.
-  if (gl_ && attributes_.noExtensions)
+  if (gl_ && attributes_.webGL)
     gl_->EnableFeatureCHROMIUM("webgl_enable_glsl_webgl_validation");
 
   command_buffer_->SetChannelErrorCallback(
       base::Bind(&WebGraphicsContext3DCommandBufferImpl::OnGpuChannelLost,
                  weak_ptr_factory_.GetWeakPtr()));
 
   command_buffer_->SetOnConsoleMessageCallback(
       base::Bind(&WebGraphicsContext3DCommandBufferImpl::OnErrorMessage,
                  weak_ptr_factory_.GetWeakPtr()));
 
@@ skipping 263 matching lines @@
   share_group_->RemoveAllContexts();
 
   DCHECK(host_.get());
   {
     base::AutoLock lock(g_default_share_groups_lock.Get());
     g_default_share_groups.Get().erase(host_.get());
   }
 }
 
 }  // namespace content