Allow WebGL readback for Mesa llvmpipe driver

content/browser/gpu/gpu_process_host.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/browser/gpu/gpu_process_host.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 122 matching lines @@
   switches::kEnableSandboxLogging,
   switches::kShowMacOverlayBorders,
 #endif
 #if defined(USE_OZONE)
   switches::kOzonePlatform,
 #endif
 #if defined(USE_X11) && !defined(OS_CHROMEOS)
   switches::kWindowDepth,
   switches::kX11Display,
 #endif
+  switches::kGpuTestingGLVendor,
+  switches::kGpuTestingGLRenderer,
+  switches::kGpuTestingGLVersion,
 };
 
 enum GPUProcessLifetimeEvent {
   LAUNCHED,
   DIED_FIRST_TIME,
   DIED_SECOND_TIME,
   DIED_THIRD_TIME,
   DIED_FOURTH_TIME,
   GPU_PROCESS_LIFETIME_EVENT_MAX = 100
 };
@@ skipping 1015 matching lines @@
   TRACE_EVENT0("gpu", "GpuProcessHost::OnCacheShader");
   ClientIdToShaderCacheMap::iterator iter =
       client_id_to_shader_cache_.find(client_id);
   // If the cache doesn't exist then this is an off the record profile.
   if (iter == client_id_to_shader_cache_.end())
     return;
   iter->second->Cache(GetShaderPrefixKey() + ":" + key, shader);
 }
 
 }  // namespace content