Trying changes to see the perfomance impact on Mac....

chrome/browser/metrics/thread_watcher.cc

Index: chrome/browser/metrics/thread_watcher.cc
===================================================================
--- chrome/browser/metrics/thread_watcher.cc	(revision 76170)
+++ chrome/browser/metrics/thread_watcher.cc	(working copy)
@@ -2,14 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#if 0
-
 #include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/metrics/thread_watcher.h"
 #include "chrome/common/notification_service.h"
 
+#if defined(OS_WIN)
+#include <Objbase.h>
+#endif
+
 // static
 const int ThreadWatcher::kPingCount = 3;
 
@@ -42,19 +44,20 @@
   DCHECK_GE(sleep_time.InMilliseconds(), 0);
   DCHECK_GE(unresponsive_time.InMilliseconds(), sleep_time.InMilliseconds());
 
-  // If we are not on WATCHDOG thread, then post a task to call StartWatching on
-  // WATCHDOG thread.
-  if (!BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG)) {
-    BrowserThread::PostTask(
-        BrowserThread::WATCHDOG,
-        FROM_HERE,
-        NewRunnableFunction(
-            &ThreadWatcher::StartWatching,
-            thread_id, thread_name, sleep_time, unresponsive_time));
+  // If we are not on WatchDogThread, then post a task to call StartWatching on
+  // WatchDogThread.
+  if (!WatchDogThread::CurrentlyOnWatchDogThread()) {
+    MessageLoop* message_loop = WatchDogThread::CurrentMessageLoop();
+    if (message_loop)
+      message_loop->PostTask(
+          FROM_HERE,
+          NewRunnableFunction(
+              &ThreadWatcher::StartWatching,
+              thread_id, thread_name, sleep_time, unresponsive_time));
     return;
   }
 
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
 
   // Create a new thread watcher object for the given thread and activate it.
   ThreadWatcher* watcher =
@@ -64,7 +67,7 @@
 }
 
 void ThreadWatcher::ActivateThreadWatching() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   if (active_) return;
   active_ = true;
   ping_count_ = kPingCount;
@@ -74,14 +77,14 @@
 }
 
 void ThreadWatcher::DeActivateThreadWatching() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   active_ = false;
   ping_count_ = 0;
   method_factory_.RevokeAll();
 }
 
 void ThreadWatcher::WakeUp() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   // There is some user activity, PostPingMessage task of thread watcher if
   // needed.
   if (!active_) return;
@@ -95,7 +98,7 @@
 }
 
 void ThreadWatcher::PostPingMessage() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   // If we have stopped watching or if the user is idle, then stop sending
   // ping messages.
   if (!active_ || ping_count_ <= 0)
@@ -126,7 +129,7 @@
 }
 
 void ThreadWatcher::OnPongMessage(uint64 ping_sequence_number) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   // Record watched thread's response time.
   base::TimeDelta response_time = base::TimeTicks::Now() - ping_time_;
   histogram_->AddTime(response_time);
@@ -152,7 +155,7 @@
 }
 
 bool ThreadWatcher::OnCheckResponsiveness(uint64 ping_sequence_number) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   // If we have stopped watching then consider thread as responding.
   if (!active_)
     return true;
@@ -178,7 +181,11 @@
                                   Task* callback_task) {
   // This method is called on watched thread.
   DCHECK(BrowserThread::CurrentlyOn(thread_id));
-  BrowserThread::PostTask(BrowserThread::WATCHDOG, FROM_HERE, callback_task);
+  MessageLoop* message_loop = WatchDogThread::CurrentMessageLoop();
+  if (message_loop)
+    message_loop->PostTask(FROM_HERE, callback_task);
+  else
+    delete callback_task;
 }
 
 //------------------------------------------------------------------------------
@@ -191,22 +198,15 @@
     : last_wakeup_time_(base::TimeTicks::Now()) {
   // Assert we are not running on WATCHDOG thread. Would be ideal to assert we
   // are on UI thread, but Unit tests are not running on UI thread.
-  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
-  DCHECK(!global_);
+  DCHECK(!WatchDogThread::CurrentlyOnWatchDogThread());
+  CHECK(!global_);
   global_ = this;
   // Register Notifications observer.
-#if defined(OS_WIN)
   MetricsService::SetupNotifications(&registrar_, this);
-#endif
 }
 
 ThreadWatcherList::~ThreadWatcherList() {
   base::AutoLock auto_lock(lock_);
-  while (!registered_.empty()) {
-    RegistrationList::iterator it = registered_.begin();
-    delete it->second;
-    registered_.erase(it->first);
-  }
   DCHECK(this == global_);
   global_ = NULL;
 }
@@ -224,15 +224,16 @@
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!global_)
     return;
-  base::AutoLock auto_lock(global_->lock_);
-  for (RegistrationList::iterator it = global_->registered_.begin();
-       global_->registered_.end() != it;
-       ++it)
-    BrowserThread::PostTask(
-        BrowserThread::WATCHDOG,
+
+  // Remove all notifications for all watched threads.
+  RemoveNotifications();
+
+  // Delete all thread watcher objects on WatchDogThread.
+  MessageLoop* message_loop = WatchDogThread::CurrentMessageLoop();
+  if (message_loop)
+    message_loop->PostTask(
         FROM_HERE,
-        NewRunnableMethod(
-            it->second, &ThreadWatcher::DeActivateThreadWatching));
+        NewRunnableMethod(global_, &ThreadWatcherList::DeleteAll));
 }
 
 // static
@@ -240,12 +241,20 @@
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!global_)
     return;
-#if defined(OS_WIN)
   base::AutoLock auto_lock(global_->lock_);
   global_->registrar_.RemoveAll();
-#endif
 }
 
+void ThreadWatcherList::DeleteAll() {
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
+  base::AutoLock auto_lock(lock_);
+  while (!registered_.empty()) {
+    RegistrationList::iterator it = registered_.begin();
+    delete it->second;
+    registered_.erase(it->first);
+  }
+}
+
 void ThreadWatcherList::Observe(NotificationType type,
                                 const NotificationSource& source,
                                 const NotificationDetails& details) {
@@ -260,15 +269,17 @@
       last_wakeup_time_ = now;
     }
   }
-  if (need_to_awaken)
-    BrowserThread::PostTask(
-        BrowserThread::WATCHDOG,
-        FROM_HERE,
-        NewRunnableMethod(this, &ThreadWatcherList::WakeUpAll));
+  if (need_to_awaken) {
+    MessageLoop* message_loop = WatchDogThread::CurrentMessageLoop();
+    if (message_loop)
+      message_loop->PostTask(
+          FROM_HERE,
+          NewRunnableMethod(this, &ThreadWatcherList::WakeUpAll));
+  }
 }
 
 void ThreadWatcherList::WakeUpAll() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::WATCHDOG));
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   base::AutoLock auto_lock(lock_);
   for (RegistrationList::iterator it = global_->registered_.begin();
        global_->registered_.end() != it;
@@ -294,42 +305,81 @@
 //------------------------------------------------------------------------------
 // WatchDogThread methods and members.
 
+// static
+base::Lock WatchDogThread::lock_;
+// static
+WatchDogThread* WatchDogThread::watchdog_thread_ = NULL;
+
 // The WatchDogThread object must outlive any tasks posted to the IO thread
 // before the Quit task.
 DISABLE_RUNNABLE_METHOD_REFCOUNT(WatchDogThread);
 
-WatchDogThread::WatchDogThread()
-    : BrowserProcessSubThread(BrowserThread::WATCHDOG) {
+WatchDogThread::WatchDogThread() : Thread("WATCHDOG") {
 }
 
 WatchDogThread::~WatchDogThread() {
-  // Remove all notifications for all watched threads.
-  ThreadWatcherList::RemoveNotifications();
   // We cannot rely on our base class to stop the thread since we want our
   // CleanUp function to run.
   Stop();
 }
 
+void WatchDogThread::StartWatchingAll() {
+  const base::TimeDelta kSleepTime = base::TimeDelta::FromSeconds(5);
+  const base::TimeDelta kUnresponsiveTime = base::TimeDelta::FromSeconds(10);
+  if (BrowserThread::IsMessageLoopValid(BrowserThread::UI))
+    ThreadWatcher::StartWatching(BrowserThread::UI, "UI", kSleepTime,
+                                 kUnresponsiveTime);
+  if (BrowserThread::IsMessageLoopValid(BrowserThread::IO))
+    ThreadWatcher::StartWatching(BrowserThread::IO, "IO", kSleepTime,
+                                 kUnresponsiveTime);
+  if (BrowserThread::IsMessageLoopValid(BrowserThread::DB))
+    ThreadWatcher::StartWatching(BrowserThread::DB, "DB", kSleepTime,
+                                 kUnresponsiveTime);
+  if (BrowserThread::IsMessageLoopValid(BrowserThread::FILE))
+    ThreadWatcher::StartWatching(BrowserThread::FILE, "FILE", kSleepTime,
+                                 kUnresponsiveTime);
+  if (BrowserThread::IsMessageLoopValid(BrowserThread::CACHE))
+    ThreadWatcher::StartWatching(BrowserThread::CACHE, "CACHE", kSleepTime,
+                                 kUnresponsiveTime);
+}
+
+// static
+MessageLoop* WatchDogThread::CurrentMessageLoop() {
+  base::AutoLock lock(lock_);
+  MessageLoop* message_loop = watchdog_thread_ ?
+      watchdog_thread_->message_loop() : NULL;
+  return message_loop;
+}
+
+// static
+bool WatchDogThread::CurrentlyOnWatchDogThread() {
+  base::AutoLock lock(lock_);
+  return watchdog_thread_ &&
+    watchdog_thread_->message_loop() == MessageLoop::current();
+}
+
 void WatchDogThread::Init() {
   // This thread shouldn't be allowed to perform any blocking disk I/O.
   base::ThreadRestrictions::SetIOAllowed(false);
 
-  BrowserProcessSubThread::Init();
+#if defined(OS_WIN)
+  // Initializes the COM library on the current thread.
+  CoInitialize(NULL);
+#endif
 
+  base::AutoLock lock(lock_);
+  watchdog_thread_ = this;
+}
+
+void WatchDogThread::CleanUp() {
+  base::AutoLock lock(lock_);
+  watchdog_thread_ = NULL;
+}
+
+void WatchDogThread::CleanUpAfterMessageLoopDestruction() {
 #if defined(OS_WIN)
-  const base::TimeDelta kSleepTime = base::TimeDelta::FromSeconds(5);
-  const base::TimeDelta kUnresponsiveTime = base::TimeDelta::FromSeconds(10);
-  ThreadWatcher::StartWatching(BrowserThread::UI, "UI", kSleepTime,
-                               kUnresponsiveTime);
-  ThreadWatcher::StartWatching(BrowserThread::IO, "IO", kSleepTime,
-                               kUnresponsiveTime);
-  ThreadWatcher::StartWatching(BrowserThread::DB, "DB", kSleepTime,
-                               kUnresponsiveTime);
-  ThreadWatcher::StartWatching(BrowserThread::FILE, "FILE", kSleepTime,
-                               kUnresponsiveTime);
-  ThreadWatcher::StartWatching(BrowserThread::CACHE, "CACHE", kSleepTime,
-                               kUnresponsiveTime);
+  // Closes the COM library on the current thread. CoInitialize must
+  // be balanced by a corresponding call to CoUninitialize.
+  CoUninitialize();
 #endif
 }
-
-#endif  // 0