Added a callback in nuplayer via informational event to signal the start of video rendering

Change-Id: Id7b9b82d4e5467ad8701bfbad4dcc5070f3703cf
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
index 1f13955..8a75f83 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
@@ -47,6 +47,7 @@
       mHasVideo(false),
       mSyncQueues(false),
       mPaused(false),
+      mVideoRenderingStarted(false),
       mLastPositionUpdateUs(-1ll),
       mVideoLateByUs(0ll) {
 }
@@ -387,9 +388,20 @@
     mVideoQueue.erase(mVideoQueue.begin());
     entry = NULL;
 
+    if (!mVideoRenderingStarted) {
+        mVideoRenderingStarted = true;
+        notifyVideoRenderingStart();
+    }
+
     notifyPosition();
 }
 
+void NuPlayer::Renderer::notifyVideoRenderingStart() {
+    sp<AMessage> notify = mNotify->dup();
+    notify->setInt32("what", kWhatVideoRenderingStart);
+    notify->post();
+}
+
 void NuPlayer::Renderer::notifyEOS(bool audio, status_t finalResult) {
     sp<AMessage> notify = mNotify->dup();
     notify->setInt32("what", kWhatEOS);