Remove theoretical race condition between Stop() and Initialize().

Initialize() could acquire lock_ and launch a new thread_ while Stop() had
un-lock_'d and was joining the old thread.  If that happened then Stop() would
silently leak the new thread when it re-acquired lock_ and set thread_ to NULL.

This also removes a cheap but unnecessary lock/unlock pair and clarifies the
function a bit.

Tested: built & ran media_unittests.

Patch by fischman@chromium.org:
http://codereview.chromium.org/6531012/

TEST=none
BUG=none

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@75212 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 5 deletions

diff --git a/media/filters/video_renderer_base.cc b/media/filters/video_renderer_base.cc
index 857b9f8..9ed236b 100644
--- a/media/filters/video_renderer_base.cc
+++ b/media/filters/video_renderer_base.cc
@@ -106,6 +106,7 @@ void VideoRendererBase::Flush(FilterCallback* callback) {
 void VideoRendererBase::Stop(FilterCallback* callback) {
   DCHECK_EQ(pending_reads_, 0);
 
+  base::PlatformThreadHandle old_thread_handle = base::kNullThreadHandle;
   {
     base::AutoLock auto_lock(lock_);
     state_ = kStopped;
@@ -115,14 +116,13 @@ void VideoRendererBase::Stop(FilterCallback* callback) {
       // Signal the thread since it's possible to get stopped with the video
       // thread waiting for a read to complete.
       frame_available_.Signal();
-      {
-        base::AutoUnlock auto_unlock(lock_);
-        base::PlatformThread::Join(thread_);
-      }
+      old_thread_handle = thread_;
       thread_ = base::kNullThreadHandle;
     }
-
   }
+  if (old_thread_handle)
+    base::PlatformThread::Join(old_thread_handle);
+
   // Signal the subclass we're stopping.
   OnStop(callback);
 }