Refactor MediaSourceDelegate destruction.

content/renderer/media/android/webmediaplayer_android.cc

 // Copyright 2013 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 "content/renderer/media/android/webmediaplayer_android.h"
 
 #include <limits>
 
 #include "base/android/build_info.h"
 #include "base/bind.h"
@@ skipping 183 matching lines @@
 
   {
     base::AutoLock auto_lock(current_frame_lock_);
     current_frame_ = NULL;
   }
 
   if (delegate_)
     delegate_->PlayerGone(this);
 
   stream_texture_factory_->RemoveObserver(this);
+
+  if (media_source_delegate_) {
+    // Part of |media_source_delegate_| needs to be stopped on the media thread.
+    // Wait until |media_source_delegate_| is fully stopped before tearing
+    // down other objects.
+    base::WaitableEvent waiter(false, false);
+    media_source_delegate_->Stop(
+        base::Bind(&base::WaitableEvent::Signal, base::Unretained(&waiter)));

[qinmin, 2014/09/26 18:06:50]

How about moving this waitableEvent into MediaSourceDelegate::Stop()? 
With the current change, MediaSourceDelegate::Stop() implicitly implies that
only a waitableEvent::signal callback can be accept as the callback will be
executed on another thread. So developers can easily make a mistake there if
they don't read the implementation.

By moving the waitableEvent into MediaSourceDelegate::Stop(), we don't need to
pass a CB into MSD and there is no need to worry about what kind of callbacks
can be passed. 

[xhwang, 2014/09/26 21:06:57]

My Clank checkout is broken.. I'll land this CL as is and address this comment
later.

+    waiter.Wait();
+  }
 }
 
 void WebMediaPlayerAndroid::load(LoadType load_type,
                                  const blink::WebURL& url,
                                  CORSMode cors_mode) {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   media::ReportMediaSchemeUma(GURL(url));
 
   switch (load_type) {
     case LoadTypeURL:
@@ skipping 1620 matching lines @@
 
 bool WebMediaPlayerAndroid::IsHLSStream() const {
   std::string mime;
   GURL url = redirected_url_.is_empty() ? url_ : redirected_url_;
   if (!net::GetMimeTypeFromFile(base::FilePath(url.path()), &mime))
     return false;
   return !mime.compare("application/x-mpegurl");
 }
 
 }  // namespace content