ThreadWatcher - enable it in CANARY channel and updated the comments to

chrome/browser/metrics/thread_watcher.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/metrics/thread_watcher.h"
 
 #include <math.h>  // ceil
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 521 matching lines @@
 
   // This method is deferred in relationship to its StopWatchingAll()
   // counterpart. If a previous initialization has already happened, or if
   // stop has been called, there's nothing left to do here.
   if (g_thread_watcher_list_ || g_stopped_)
     return;
 
   ThreadWatcherList* thread_watcher_list = new ThreadWatcherList();
   CHECK(thread_watcher_list);
 
-  // Disable ThreadWatcher in Canary channel.
+  // TODO(rtenneti): Because we don't generate crash dumps for ThreadWatcher in
+  // stable channel, disable ThreadWatcher in stable and unknown channels. We
+  // will also not collect histogram data in these channels until
+  // http://crbug.com/426203 is fixed.
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
-  if (channel == chrome::VersionInfo::CHANNEL_CANARY ||
-      channel == chrome::VersionInfo::CHANNEL_STABLE ||
+  if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_UNKNOWN) {
     return;
   }
 
   const base::TimeDelta kSleepTime =
       base::TimeDelta::FromSeconds(kSleepSeconds);
   const base::TimeDelta kUnresponsiveTime =
       base::TimeDelta::FromSeconds(kUnresponsiveSeconds);
 
   StartWatching(BrowserThread::UI, "UI", kSleepTime, kUnresponsiveTime,
@@ skipping 373 matching lines @@
 
 #if defined(OS_WIN)
   // On Windows XP, give twice the time for shutdown.
   if (base::win::GetVersion() <= base::win::VERSION_XP)
     actual_duration *= 2;
 #endif
 
   shutdown_watchdog_ = new ShutdownWatchDogThread(actual_duration);
   shutdown_watchdog_->Arm();
 }