[WVDRM] Fix for stuttering on low bandwidth

Reintroduces the play/pause rebuffering logic we eliminated
in JB zero day to fix double spins and slow startup - but
activates that logic only based on a comparison of the
current bandwidth measurement and the lowest bitrate track
in the movie.

Needs to be submitted with related changes in /frameworks/av

bug: 7230071
Change-Id: Ib3859a961bd3901a9c4df01eeab2b8b75f49aefe

proprietary/wvm/include/WVMMediaSource.h

@@ -41,7 +41,6 @@ public:
     virtual status_t read(MediaBuffer **buffer, const ReadOptions *options = NULL);
 
     void addEncryptedSize(size_t size) { mEncryptedSizes.push_back(size); }
-    bool isStalled() const { return mIsStalled; }
 
     static int sLastError;
 
@@ -87,7 +86,6 @@ private:
     bool mIsLiveStream;
     bool mNewSegment;
     bool mCryptoInitialized;
-    bool mIsStalled;
     bool mStripADTS;
 
     MediaBufferGroup *mGroup;