Add switch (for cast_shell) to defer creation of GPU process.

content/public/common/content_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 "content/public/common/content_switches.h"
 
 namespace switches {
 
 // The number of MSAA samples for canvas2D. Requires MSAA support by GPU to
 // have an effect. 0 disables MSAA.
@@ skipping 46 matching lines @@
 // Path to the exe to run for the renderer and plugin subprocesses.
 const char kBrowserSubprocessPath[]         = "browser-subprocess-path";
 
 // Dumps extra logging about plugin loading to the log file.
 const char kDebugPluginLoading[] = "debug-plugin-loading";
 
 // Sets the tile size used by composited layers.
 const char kDefaultTileWidth[]              = "default-tile-width";
 const char kDefaultTileHeight[]             = "default-tile-height";
 
+// Defer GPU process creation.  Disables default logic for starting GPU process
+// during browser main thread initialization.  Content embedder is responsible
+// for creating GPU process before it's needed.

[piman, 2015/03/26 20:26:19]

nit: I don't think the last sentence is correct. We'll still go ahead and create
the GPU channel if we need one (see
GpuProcessTransportFactory::CreateOutputSurface), this flag just disables the
prelaunch of the GPU process.

[halliwell, 2015/03/26 21:58:11]

I see, yes.  Removed this part of the comment.

+const char kDeferGpuProcessCreation[]       = "defer-gpu-process-creation";
+
 // Disable antialiasing on 2d canvas.
 const char kDisable2dCanvasAntialiasing[]   = "disable-canvas-aa";
 
 // Disables client-visible 3D APIs, in particular WebGL and Pepper 3D.
 // This is controlled by policy and is kept separate from the other
 // enable/disable switches to avoid accidentally regressing the policy
 // support for controlling access to these APIs.
 const char kDisable3DAPIs[]                 = "disable-3d-apis";
 
 // Disable gpu-accelerated 2d canvas.
@@ skipping 904 matching lines @@
 const char kEnableNpapi[]                   = "enable-npapi";
 
 #if defined(ENABLE_PLUGINS)
 // Enables the plugin power saver feature.
 const char kEnablePluginPowerSaver[] = "enable-plugin-power-saver";
 #endif
 
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches