Revert: Flapper field trial to use workerpool for sync file operations.

content/browser/renderer_host/pepper/pepper_file_message_filter.cc

Index: content/browser/renderer_host/pepper/pepper_file_message_filter.cc
diff --git a/content/browser/renderer_host/pepper/pepper_file_message_filter.cc b/content/browser/renderer_host/pepper/pepper_file_message_filter.cc
index e07bb990a01974cab3aa72a76a4b58b9386e0b33..5de7fbf19fcda606694d66f38d7f78e7f1cf80e5 100644
--- a/content/browser/renderer_host/pepper/pepper_file_message_filter.cc
+++ b/content/browser/renderer_host/pepper/pepper_file_message_filter.cc
@@ -8,10 +8,8 @@
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
-#include "base/metrics/field_trial.h"
 #include "base/platform_file.h"
 #include "base/process_util.h"
-#include "base/threading/sequenced_worker_pool.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/public/browser/browser_thread.h"
@@ -62,67 +60,20 @@ IPC::PlatformFileForTransit PlatformFileToPlatformFileForTransit(
   return file;
 }
 
-// Run a field trial comparing the effect of the FILE thread versus
-// blocking worker pool on hung-plugin reports.
-// TODO(shess): Remove once the workpool is proven superior.
-// http://crbug.com/153383
-const char* const kIOFieldTrialName = "FlapperIOThread";
-const char* const kPoolGroupName = "PoolThread";
-const char* const kFileGroupName = "FileThread";
-
-bool g_use_file_thread = true;
-
-void ActivateThreadFieldTrial() {
-  static bool activated = false;
-  if (activated)
-    return;
-
-  activated = true;
-
-  // The field trial will expire on Jan 1st, 2014.
-  scoped_refptr<base::FieldTrial> trial(
-      base::FieldTrialList::FactoryGetFieldTrial(
-          kIOFieldTrialName, 1000, kPoolGroupName, 2014, 1, 1, NULL));
-
-  // 50% goes into the FILE thread group.
-  trial->AppendGroup(kFileGroupName, 500);
-
-  g_use_file_thread = (trial->group_name() == kFileGroupName);
-}
-
 }  // namespace
 
 PepperFileMessageFilter::PepperFileMessageFilter(int child_id)
         : child_id_(child_id),
           channel_(NULL) {
-  ActivateThreadFieldTrial();
 }
 
 void PepperFileMessageFilter::OverrideThreadForMessage(
     const IPC::Message& message,
     BrowserThread::ID* thread) {
-  if (IPC_MESSAGE_CLASS(message) == PepperFileMsgStart && g_use_file_thread)
+  if (IPC_MESSAGE_CLASS(message) == PepperFileMsgStart)
     *thread = BrowserThread::FILE;
 }
 
-base::TaskRunner* PepperFileMessageFilter::OverrideTaskRunnerForMessage(
-    const IPC::Message& message) {
-  // The blocking pool provides a pool of threads to run file
-  // operations, instead of a single thread which might require
-  // queuing time.  Since these messages are synchronous as sent from
-  // the plugin, the sending thread cannot send a new message until
-  // this one returns, so there is no need to sequence tasks here.  If
-  // the plugin has multiple threads, it cannot make assumptions about
-  // ordering of IPC message sends, so it cannot make assumptions
-  // about ordering of operations caused by those IPC messages.
-  if (IPC_MESSAGE_CLASS(message) == PepperFileMsgStart) {
-    // Should never get here if using the FILE thread.
-    DCHECK(!g_use_file_thread);
-    return BrowserThread::GetBlockingPool();
-  }
-  return NULL;
-}
-
 bool PepperFileMessageFilter::OnMessageReceived(const IPC::Message& message,
                                                 bool* message_was_ok) {
   bool handled = true;