C2VdaBqBlockPool: Polish the retry logic

After fetching new IGBP slot times out, we should retry the fetching
when buffer released at IGBP. We use a flag
|mBufferReleasedAfterTimedOut| to catch the case that the buffer is
released between fetching timed out and setting the retry callback.
If the flag is set, then we should execute the callback immediately,
instead of waiting for the next buffer released event.

However, we forgot to reset the flag when executing the callback. It
caused we continuously retry the buffer fetching until the next buffer
released event. This CL fixes this issue.

Bug: 175489166
Test: run com.google.android.exoplayer.gts.DashTest#testH264Adaptive
      and check setMaxDequeuedBufferCount() only retry when buffer
      released
Change-Id: I8f7a36af50e5eebfcbecedc0f126c86f9427fa95

plugin_store/C2VdaBqBlockPool.cpp

@@ -603,8 +603,8 @@ private:
     sp<EventNotifier> mFetchBufferNotifier;
 
     std::mutex mBufferReleaseMutex;
-    // Set to true when the buffer release event is triggered after dequeueing
-    // buffer from IGBP times out.
+    // Set to true when the buffer release event is triggered after dequeueing buffer from IGBP
+    // times out. Reset when fetching new slot times out, or |mNotifyBlockAvailableCb| is executed.
     bool mBufferReleasedAfterTimedOut GUARDED_BY(mBufferReleaseMutex) = false;
     // The callback to notify the caller the buffer is available.
     ::base::OnceClosure mNotifyBlockAvailableCb GUARDED_BY(mBufferReleaseMutex);
@@ -855,6 +855,7 @@ void C2VdaBqBlockPool::Impl::onEventNotified() {
 
         mBufferReleasedAfterTimedOut = true;
         if (mNotifyBlockAvailableCb) {
+            mBufferReleasedAfterTimedOut = false;
             outputCb = std::move(mNotifyBlockAvailableCb);
         }
     }
@@ -1184,6 +1185,7 @@ bool C2VdaBqBlockPool::Impl::setNotifyBlockAvailableCb(::base::OnceClosure cb) {
         // If there is any buffer released after dequeueBuffer() timed out, then we could notify the
         // caller directly.
         if (mBufferReleasedAfterTimedOut) {
+            mBufferReleasedAfterTimedOut = false;
             outputCb = std::move(cb);
         } else {
             mNotifyBlockAvailableCb = std::move(cb);