Add Plugin.PpapiSyncIPCTime metric.

ppapi/proxy/plugin_dispatcher.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 "ppapi/proxy/plugin_dispatcher.h"
 
 #include <map>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_sync_channel.h"
 #include "ipc/ipc_sync_message_filter.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppp_instance.h"
 #include "ppapi/proxy/flash_clipboard_resource.h"
 #include "ppapi/proxy/flash_file_resource.h"
 #include "ppapi/proxy/flash_resource.h"
 #include "ppapi/proxy/gamepad_resource.h"
@@ skipping 177 matching lines @@
   // Allowing all async messages to unblock the renderer means more reentrancy
   // there but gives correct ordering.
   //
   // We don't want reply messages to unblock however, as they will potentially
   // end up on the wrong queue - see crbug.com/122443
   if (!msg->is_reply())
     msg->set_unblock(true);
   if (msg->is_sync()) {
     // Synchronous messages might be re-entrant, so we need to drop the lock.
     ProxyAutoUnlock unlock;
+    SCOPED_UMA_HISTOGRAM_TIMER("Plugin.PpapiSyncIPCTime");
     return SendMessage(msg);
   }
   return SendMessage(msg);
 }
 
 bool PluginDispatcher::OnMessageReceived(const IPC::Message& msg) {
   // We need to grab the proxy lock to ensure that we don't collide with the
   // plugin making pepper calls on a different thread.
   ProxyAutoLock lock;
   TRACE_EVENT2("ppapi proxy", "PluginDispatcher::OnMessageReceived",
@@ skipping 101 matching lines @@
   // once they're set. The user will have to restart to get new font prefs
   // propogated to plugins.
   if (!received_preferences_) {
     received_preferences_ = true;
     preferences_ = prefs;
   }
 }
 
 }  // namespace proxy
 }  // namespace ppapi