ThreadWatcher: fixes Start/StopWatchingAll.

chrome/browser/metrics/thread_watcher.cc

Index: chrome/browser/metrics/thread_watcher.cc
diff --git a/chrome/browser/metrics/thread_watcher.cc b/chrome/browser/metrics/thread_watcher.cc
index 1737593f294129536d4f1593a5b71b42241bea4a..8246b3eaafb963e7d66c6a2cdeef3d013f86b31b 100644
--- a/chrome/browser/metrics/thread_watcher.cc
+++ b/chrome/browser/metrics/thread_watcher.cc
@@ -409,6 +409,8 @@ bool ThreadWatcher::IsVeryUnresponsive() {
 // static
 ThreadWatcherList* ThreadWatcherList::g_thread_watcher_list_ = NULL;
 // static
+bool ThreadWatcherList::g_stopped_ = false;
+// static
 const int ThreadWatcherList::kSleepSeconds = 1;
 // static
 const int ThreadWatcherList::kUnresponsiveSeconds = 2;
@@ -443,6 +445,10 @@ void ThreadWatcherList::StartWatchingAll(const CommandLine& command_line) {
   ThreadWatcherObserver::SetupNotifications(
       base::TimeDelta::FromSeconds(kSleepSeconds * unresponsive_threshold));
 
+  WatchDogThread::PostTask(
+      FROM_HERE,
+      base::Bind(&ThreadWatcherList::SetStopped, false));
+
   WatchDogThread::PostDelayedTask(
       FROM_HERE,
       base::Bind(&ThreadWatcherList::InitializeAndStartWatching,
@@ -635,6 +641,12 @@ void ThreadWatcherList::InitializeAndStartWatching(
     const CrashOnHangThreadMap& crash_on_hang_threads) {
   DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
 
+  // 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);
 
@@ -700,6 +712,9 @@ void ThreadWatcherList::DeleteAll() {
   }
 
   DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
+
+  SetStopped(true);
+
   if (!g_thread_watcher_list_)
     return;
 
@@ -725,6 +740,12 @@ ThreadWatcher* ThreadWatcherList::Find(const BrowserThread::ID& thread_id) {
   return it->second;
 }
 
+// static
+void ThreadWatcherList::SetStopped(bool stopped) {
+  DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
+  g_stopped_ = stopped;
+}
+
 // ThreadWatcherObserver methods and members.
 //
 // static