added gpu_benchmarking_extension boilerplate and hooked it up to a new switch.

content/browser/renderer_host/render_process_host_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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #if defined(OS_WIN)
@@ skipping 659 matching lines @@
     switches::kDisableWebSockets,
     switches::kDomAutomationController,
     switches::kEnableAccessibilityLogging,
     switches::kEnableBrowserPlugin,
     switches::kEnableDCHECK,
     switches::kEnableEncryptedMedia,
     switches::kEnableFixedLayout,
     switches::kEnableGamepad,
     switches::kEnableGPUServiceLogging,
     switches::kEnableGPUClientLogging,
+    switches::kEnableGpuBenchmarking,

[nduca, 2012/06/08 00:36:03]

Looks like we use all-caps GPU here for this kind of enum. When you find
inconsistency, you should try to follow the convention established in adjacent
code.

[dmurph, 2012/06/08 18:36:22]

Hm, well all of the switches in content_switches use 'Gpu', those two are from
gl_switches, where there are two 'GPU's and four 'Gpu's.  Since there's a
universal majority of 'Gpu', I'll leave it as that, but let me know if I should
change it still.

     switches::kEnableLogging,
     switches::kEnableMediaSource,
     switches::kEnablePeerConnection,
     switches::kEnableShadowDOM,
     switches::kEnableStrictSiteIsolation,
     switches::kEnableStyleScoped,
     switches::kDisableFullScreen,
     switches::kEnablePepperTesting,
     switches::kEnablePointerLock,
     switches::kEnablePreparsedJsCaching,
@@ skipping 669 matching lines @@
       uint64 surface_handle,
       int32 route_id,
       int32 gpu_process_host_id) {
   TRACE_EVENT0("renderer_host",
                "RenderWidgetHostImpl::OnCompositorSurfaceBuffersSwappedNoHost");
   RenderWidgetHostImpl::AcknowledgeSwapBuffers(route_id,
                                                gpu_process_host_id);
 }
 
 }  // namespace content