AudioSource: initialize variables

to prevent info leak

Bug: 27855172
Change-Id: I3d33e0a9cc5cf8a758d7b0794590b09c43a24561
diff --git a/media/libstagefright/AudioSource.cpp b/media/libstagefright/AudioSource.cpp
index 6e4a1dd..55f4361 100644
--- a/media/libstagefright/AudioSource.cpp
+++ b/media/libstagefright/AudioSource.cpp
@@ -55,8 +55,12 @@
     : mStarted(false),
       mSampleRate(sampleRate),
       mOutSampleRate(outSampleRate > 0 ? outSampleRate : sampleRate),
+      mTrackMaxAmplitude(false),
+      mStartTimeUs(0),
+      mMaxAmplitude(0),
       mPrevSampleTimeUs(0),
       mFirstSampleTimeUs(-1ll),
+      mInitialReadTimeUs(0),
       mNumFramesReceived(0),
       mNumClientOwnedBuffers(0) {
     ALOGV("sampleRate: %u, outSampleRate: %u, channelCount: %u",