Make the number of raster threads appear in chrome://gpu.

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"
 
 #include <algorithm>
@@ skipping 1002 matching lines @@
   return storage_partition_impl_;
 }
 
 static void AppendCompositorCommandLineFlags(base::CommandLine* command_line) {
   if (IsPinchVirtualViewportEnabled())
     command_line->AppendSwitch(cc::switches::kEnablePinchVirtualViewport);
 
   if (IsDelegatedRendererEnabled())
     command_line->AppendSwitch(switches::kEnableDelegatedRenderer);
 
-  if (IsImplSidePaintingEnabled())
+  if (IsImplSidePaintingEnabled()) {
     command_line->AppendSwitch(switches::kEnableImplSidePainting);
+    command_line->AppendSwitchASCII(
+        switches::kNumRasterThreads,
+        base::IntToString(NumberOfRendererRasterThreads()));
+  }
 
   if (content::IsGpuRasterizationEnabled())
     command_line->AppendSwitch(switches::kEnableGpuRasterization);
 
   if (content::IsForceGpuRasterizationEnabled())
     command_line->AppendSwitch(switches::kForceGpuRasterization);
 
   // Appending disable-gpu-feature switches due to software rendering list.
   GpuDataManagerImpl* gpu_data_manager = GpuDataManagerImpl::GetInstance();
   DCHECK(gpu_data_manager);
@@ skipping 137 matching lines @@
     switches::kIgnoreResolutionLimitsForAcceleratedVideoDecode,
     switches::kIPCConnectionTimeout,
     switches::kJavaScriptFlags,
     switches::kLoggingLevel,
     switches::kMainFrameResizesAreOrientationChanges,
     switches::kMaxUntiledLayerWidth,
     switches::kMaxUntiledLayerHeight,
     switches::kMemoryMetrics,
     switches::kNoReferrers,
     switches::kNoSandbox,
-    switches::kNumRasterThreads,

[Ken Russell (switch to Gerrit), 2014/08/29 22:41:05]

Why is this being removed from this list? Isn't it needed here to get this
argument propagated down to the renderer?

[danakj, 2014/08/29 22:42:20]

because the other code adds it to the renderer command line explicitly, we don't
just forward it along blindly. this list is flags to just copy from the browser
command line.

     switches::kPpapiInProcess,
     switches::kProfilerTiming,
     switches::kReduceSecurityForTesting,
     switches::kRegisterPepperPlugins,
     switches::kRendererAssertTest,
     switches::kRendererStartupDialog,
     switches::kSendV8IdleNotificationAfterCommit,
     switches::kShowPaintRects,
     switches::kSitePerProcess,
     switches::kStatsCollectionController,
@@ skipping 1160 matching lines @@
 }
 
 void RenderProcessHostImpl::OnDeletedGpuMemoryBuffer(
     gfx::GpuMemoryBufferType type,
     const gfx::GpuMemoryBufferId& id) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   GpuMemoryBufferImpl::DeletedByChildProcess(type, id, GetHandle());
 }
 
 }  // namespace content