Bug 1420819 - run MediaCache::Flush() off the main thread. r=bechen,gerald

MozReview-Commit-ID: 4QR1TvORZlz

--HG--
extra : rebase_source : 1451c437c6daf80b15b6f23552900e2ef2467324
extra : intermediate-source : 3a0bdc29f6c70ac2a1479dbc7f10ebbd52a68456
extra : source : da25c3537d9b4665dff55f615467bcb62e5dde56

dom/media/MediaCache.cpp

@@ -427,6 +427,8 @@ protected:
   // end
   void Truncate();
 
+  void FlushInternal(AutoLock&);
+
   // There is at most one file-backed media cache.
   // It is owned by all MediaCacheStreams that use it.
   // This is a raw pointer set by GetMediaCache(), and reset by ~MediaCache(),
@@ -695,13 +697,10 @@ MediaCacheStream::BlockList::NotifyBlockSwapped(int32_t aBlockIndex1,
 }
 
 void
-MediaCache::Flush()
+MediaCache::FlushInternal(AutoLock& aLock)
 {
-  NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
-  AutoLock lock(mMonitor);
-
   for (uint32_t blockIndex = 0; blockIndex < mIndex.Length(); ++blockIndex) {
-    FreeBlock(lock, blockIndex);
+    FreeBlock(aLock, blockIndex);
   }
 
   // Truncate index array.
@@ -711,6 +710,18 @@ MediaCache::Flush()
   mBlockCache->Flush();
 }
 
+void
+MediaCache::Flush()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
+    "MediaCache::Flush", [self = RefPtr<MediaCache>(this)]() {
+      AutoLock lock(self->mMonitor);
+      self->FlushInternal(lock);
+    });
+  sThread->Dispatch(r.forget());
+}
+
 void
 MediaCache::CloseStreamsForPrivateBrowsing()
 {