Add a hang monitor for Pepper plugins

chrome/browser/memory_details.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 "chrome/browser/memory_details.h"
 
 #include "base/bind.h"
 #include "base/file_version_info.h"
 #include "base/metrics/histogram.h"
 #include "base/process_util.h"
@@ skipping 89 matching lines @@
   name = rhs.name;
   process_name = rhs.process_name;
   processes = rhs.processes;
   return *this;
 }
 
 // About threading:
 //
 // This operation will hit no fewer than 3 threads.
 //
-// The ChildProcessInfo::Iterator can only be accessed from the IO thread.
+// The BrowserChildProcessHostIterator can only be accessed from the IO thread.
 //
 // The RenderProcessHostIterator can only be accessed from the UI thread.
 //
 // This operation can take 30-100ms to complete.  We never want to have
 // one task run for that long on the UI or IO threads.  So, we run the
 // expensive parts of this operation over on the file thread.
 //
 void MemoryDetails::StartFetch() {
   // This might get called from the UI or FILE threads, but should not be
   // getting called from the IO thread.
@@ skipping 303 matching lines @@
   UMA_HISTOGRAM_COUNTS_100("Memory.PepperPluginProcessCount",
       pepper_plugin_count);
   UMA_HISTOGRAM_COUNTS_100("Memory.RendererProcessCount", renderer_count);
   UMA_HISTOGRAM_COUNTS_100("Memory.WorkerProcessCount", worker_count);
   // TODO(viettrungluu): Do we want separate counts for the other
   // (platform-specific) process types?
 
   int total_sample = static_cast<int>(aggregate_memory / 1000);
   UMA_HISTOGRAM_MEMORY_MB("Memory.Total", total_sample);
 }