Rename RecordThread::mInputBytes to the more generic mBufferSize

This prepares for using it in PlaybackThreads later

Change-Id: Id90a92aa6372e4b69914b0008cef07296ca5d6a3
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index b1b33b0..7be6043 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -901,7 +901,7 @@
             int32_t                             *mRsmpOutBuffer;
             int16_t                             *mRsmpInBuffer;
             size_t                              mRsmpInIndex;
-            size_t                              mInputBytes;
+            size_t                              mBufferSize;    // stream buffer size for read()
             const uint32_t                      mReqChannelCount;
             const uint32_t                      mReqSampleRate;
             ssize_t                             mBytesRead;