DO NOT MERGE MPEG4Extractor: ensure kKeyTrackID exists before creating an MPEG4Source as track.

GenericSource: return error when no track exists.

SampleIterator: make sure mSamplesPerChunk is not zero before using it as divisor.

Bug: 21657957
Bug: 23705695
Bug: 22802344
Bug: 28799341
Change-Id: I7664992ade90b935d3f255dcd43ecc2898f30b04
(cherry picked from commit 0386c91)
(cherry picked from commit b016207)

Author: Wei Jia

media/libstagefright/MPEG4Extractor.cpp

@@ -883,6 +883,11 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
             }
 
             if (isTrack) {
+                int32_t trackId;
+                // There must be exact one track header per track.
+                if (!mLastTrack->meta->findInt32(kKeyTrackID, &trackId)) {
+                    mLastTrack->skipTrack = true;
+                }
                 if (mLastTrack->skipTrack) {
                     Track *cur = mFirstTrack;
 

media/libstagefright/SampleIterator.cpp

@@ -84,6 +84,11 @@ status_t SampleIterator::seekTo(uint32_t sampleIndex) {
 
     CHECK(sampleIndex < mStopChunkSampleIndex);
 
+    if (mSamplesPerChunk == 0) {
+        ALOGE("b/22802344");
+        return ERROR_MALFORMED;
+    }
+
     uint32_t chunk =
         (sampleIndex - mFirstChunkSampleIndex) / mSamplesPerChunk
         + mFirstChunk;