Bug 1747282: dom/media/File* cleanup r=bryce

Differential Revision: https://phabricator.services.mozilla.com/D138509

dom/media/FileBlockCache.cpp

@@ -31,8 +31,7 @@ static void CloseFD(PRFileDesc* aFD) {
 }
 
 void FileBlockCache::SetCacheFile(PRFileDesc* aFD) {
-  LOG("SetFD(aFD=%p) mBackgroundET=%p", aFD, mBackgroundET.get());
-
+  LOG("SetCacheFile aFD=%p", aFD);
   if (!aFD) {
     // Failed to get a temporary file. Shutdown.
     Close();
@@ -44,6 +43,8 @@ void FileBlockCache::SetCacheFile(PRFileDesc* aFD) {
   }
   {
     MutexAutoLock lock(mDataMutex);
+    LOG("SetFileCache mBackgroundET=%p, mIsWriteScheduled %d",
+        mBackgroundET.get(), mIsWriteScheduled);
     if (mBackgroundET) {
       // Still open, complete the initialization.
       mInitialized = true;
@@ -317,8 +318,8 @@ nsresult FileBlockCache::MoveBlockInFile(int32_t aSourceBlockIndex,
 }
 
 void FileBlockCache::PerformBlockIOs() {
-  MOZ_ASSERT(mBackgroundET->IsOnCurrentThread());
   MutexAutoLock mon(mDataMutex);
+  MOZ_ASSERT(mBackgroundET->IsOnCurrentThread());
   NS_ASSERTION(mIsWriteScheduled, "Should report write running or scheduled.");
 
   LOG("Run() mFD=%p mBackgroundET=%p", mFD, mBackgroundET.get());

dom/media/FileMediaResource.cpp

@@ -59,6 +59,7 @@ nsresult FileMediaResource::Open(nsIStreamListener** aStreamListener) {
   *aStreamListener = nullptr;
   nsresult rv = NS_OK;
 
+  MutexAutoLock lock(mLock);
   // The channel is already open. We need a synchronous stream that
   // implements nsISeekableStream, so we have to find the underlying
   // file and reopen it