Prevent reentrant cleanup events for idle delegates.

content/renderer/media/renderer_webmediaplayer_delegate.cc

 // Copyright 2015 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/renderer_webmediaplayer_delegate.h"
 
 #include <stdint.h>
 
 #include "base/auto_reset.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 202 matching lines @@
     return;
   }
 
   idle_delegate_map_.erase(delegate_id);
   if (idle_delegate_map_.empty())
     idle_cleanup_timer_.Stop();
 }
 
 void RendererWebMediaPlayerDelegate::CleanupIdleDelegates(
     base::TimeDelta timeout) {
+  // Drop reentrant cleanups which can occur during forced suspension when the
+  // number of idle delegates is too high for a given device.
+  if (idle_cleanup_running_)
+    return;
+
   // Iterate over the delegates and suspend the idle ones. Note: The call to
   // OnHidden() can trigger calls into RemoveIdleDelegate(), so for iterator

[watk, 2016/09/27 20:58:30]

unrelated, but if you're making another change, "OnHidden" is out of date I
think.

[DaleCurtis, 2016/09/27 21:03:49]

Done.

   // validity we set |idle_cleanup_running_| to true and defer deletions.
+  DCHECK(!idle_cleanup_running_);
   base::AutoReset<bool> scoper(&idle_cleanup_running_, true);

[watk, 2016/09/27 20:58:30]

Might make sense to consolidate the comments and put this right below the early
return.

[DaleCurtis, 2016/09/27 21:03:49]

Hmm, don't like separating the comments like that, so going to keep it as is
unless you feel strongly.

   const base::TimeTicks now = tick_clock_->NowTicks();
   for (auto& idle_delegate_entry : idle_delegate_map_) {
     if (now - idle_delegate_entry.second > timeout) {
       id_map_.Lookup(idle_delegate_entry.first)->OnSuspendRequested(false);
 
       // Whether or not the player accepted the suspension, mark it for removal
       // from future polls to avoid running the timer forever.
       idle_delegate_entry.second = base::TimeTicks();
     }
   }
@@ skipping 31 matching lines @@
 #endif  // OS_ANDROID
 
   is_playing_background_video_ = is_playing;
 }
 
 void RendererWebMediaPlayerDelegate::OnDestruct() {
   delete this;
 }
 
 }  // namespace media