Prelaunch GPU process after 10 seconds.

This will happen if the --prelaunch-gpu-process command line switch is present or for 5% of users in a field trial.

This is so we can collect some stats of GPU capabilities.

TEST=try, check --prelaunch-gpu-process works
BUG=none

Review URL: http://codereview.chromium.org/3119002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@55510 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 17 insertions, 4 deletions

diff --git a/chrome/renderer/render_thread.cc b/chrome/renderer/render_thread.cc
index 8ea6c08..cefea46 100644
--- a/chrome/renderer/render_thread.cc
+++ b/chrome/renderer/render_thread.cc
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/command_line.h"
+#include "base/field_trial.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/nullable_string16.h"
@@ -116,6 +117,9 @@ static const double kInitialIdleHandlerDelayS = 1.0 /* seconds */;
 static const double kInitialExtensionIdleHandlerDelayS = 5.0 /* seconds */;
 static const int64 kMaxExtensionIdleHandlerDelayS = 5*60 /* seconds */;
 
+static const int kPrelauchGpuPercentage = 5;
+static const int kPrelauchGpuProcessDelayMS = 10000;
+
 // Keep the global RenderThread in a TLS slot so it is impossible to access
 // incorrectly from the wrong thread.
 static base::LazyInstance<base::ThreadLocalPointer<RenderThread> > lazy_tls(
@@ -268,10 +272,19 @@ void RenderThread::Init() {
 
   // Establish a channel to the GPU process asynchronously if requested. If the
   // channel is established in time, EstablishGpuChannelSync will not block when
-  // it is later called.
-  if (CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kPrelaunchGpuProcess)) {
-    EstablishGpuChannel();
+  // it is later called. Delays by a fixed period of time to avoid loading the
+  // GPU immediately in an attempt to not slow startup time.
+  scoped_refptr<FieldTrial> prelaunch_trial(
+      new FieldTrial("PrelaunchGpuProcessExperiment", 100));
+  int prelaunch_group = prelaunch_trial->AppendGroup("prelaunch_gpu_process",
+                                                     kPrelauchGpuPercentage);
+  if (prelaunch_group == prelaunch_trial->group() ||
+      CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kPrelaunchGpuProcess)) {
+    message_loop()->PostDelayedTask(FROM_HERE,
+                                    task_factory_->NewRunnableMethod(
+                                        &RenderThread::EstablishGpuChannel),
+                                    kPrelauchGpuProcessDelayMS);
   }
 }