Update from chromium https://crrev.com/301315

gpu/command_buffer/service/gpu_switches.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 "gpu/command_buffer/service/gpu_switches.h"
 #include "base/basictypes.h"
 
 namespace switches {
 
 // Always return success when compiling a shader. Linking will still fail.
@@ skipping 38 matching lines @@
 // Sets the maximum size of the in-memory gpu program cache, in kb
 const char kGpuProgramCacheSizeKb[]         = "gpu-program-cache-size-kb";
 
 // Disables the GPU shader on disk cache.
 const char kDisableGpuShaderDiskCache[]     = "disable-gpu-shader-disk-cache";
 
 // Allows async texture uploads (off main thread) via GL context sharing.
 const char kEnableShareGroupAsyncTextureUpload[] =
     "enable-share-group-async-texture-upload";
 
+// Simulates shared textures when share groups are not available. Not available
+// everywhere.
+const char kEnableThreadedTextureMailboxes[] =
+    "enable-threaded-texture-mailboxes";
+
 const char* kGpuSwitches[] = {
   kCompileShaderAlwaysSucceeds,
   kDisableGLErrorLimit,
   kDisableGLSLTranslator,
   kDisableGpuDriverBugWorkarounds,
   kDisableShaderNameHashing,
   kEnableGPUCommandLogging,
   kEnableGPUDebugging,
   kEnableGPUServiceLoggingGPU,
   kDisableGpuProgramCache,
   kEnforceGLMinimums,
   kForceGpuMemAvailableMb,
   kGpuDriverBugWorkarounds,
   kGpuProgramCacheSizeKb,
   kDisableGpuShaderDiskCache,
   kEnableShareGroupAsyncTextureUpload,
 };
 
 const int kNumGpuSwitches = arraysize(kGpuSwitches);
 
 }  // namespace switches