Don't call Thread::CleanUp() before the MessageLoop destruction observers have run.

This is consistent with the comment for Thread::CleanUp(), which says it runs after the message loop has "stopped".
Certain consumers depend on this ordering to avoid accessing variables which are deleted by Thread::CleanUp().

BUG=39723
TEST=ThreadTest.CleanUp
Review URL: http://codereview.chromium.org/1540002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@44323 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 20 deletions

diff --git a/base/thread.cc b/base/thread.cc
index aeaa0a1..e916f2c 100644
--- a/base/thread.cc
+++ b/base/thread.cc
@@ -35,7 +35,7 @@ struct Thread::StartupData {
         event(false, false) {}
 };
 
-Thread::Thread(const char *name)
+Thread::Thread(const char* name)
     : stopping_(false),
       startup_data_(NULL),
       thread_(0),
@@ -134,25 +134,30 @@ void Thread::Run(MessageLoop* message_loop) {
 }
 
 void Thread::ThreadMain() {
-  // The message loop for this thread.
-  MessageLoop message_loop(startup_data_->options.message_loop_type);
-
-  // Complete the initialization of our Thread object.
-  thread_id_ = PlatformThread::CurrentId();
-  PlatformThread::SetName(name_.c_str());
-  ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
-  message_loop.set_thread_name(name_);
-  message_loop_ = &message_loop;
-
-  // Let the thread do extra initialization.
-  // Let's do this before signaling we are started.
-  Init();
-
-  startup_data_->event.Signal();
-  // startup_data_ can't be touched anymore since the starting thread is now
-  // unlocked.
+  {
+    // The message loop for this thread.
+    MessageLoop message_loop(startup_data_->options.message_loop_type);
+
+    // Complete the initialization of our Thread object.
+    thread_id_ = PlatformThread::CurrentId();
+    PlatformThread::SetName(name_.c_str());
+    ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
+    message_loop.set_thread_name(name_);
+    message_loop_ = &message_loop;
+
+    // Let the thread do extra initialization.
+    // Let's do this before signaling we are started.
+    Init();
+
+    startup_data_->event.Signal();
+    // startup_data_ can't be touched anymore since the starting thread is now
+    // unlocked.
+
+    Run(message_loop_);
+    // Destroy |message_loop| upon leaving this scope.
+  }
 
-  Run(message_loop_);
+  message_loop_ = NULL;
 
   // Let the thread do extra cleanup.
   CleanUp();
@@ -161,7 +166,6 @@ void Thread::ThreadMain() {
   DCHECK(GetThreadWasQuitProperly());
 
   // We can't receive messages anymore.
-  message_loop_ = NULL;
   thread_id_ = 0;
 }