Resolving createByteBufferFromABuffer null input

It was found that createByteBufferFromABuffer was recieving a NULL buffer in bug
22726278. Based on returning NULL when buffer->base() == NULL, returning NULL
when buffer == NULL. This does not fix bug 22726278 - but address a problem found
while looking into it.

Bug: 22726278
Change-Id: I933b6a4a535d803576a4cdd7a1ffaf4a428c3201

media/jni/android_media_MediaCodec.cpp

@@ -440,6 +440,12 @@ status_t JMediaCodec::createByteBufferFromABuffer(
     // if this is an ABuffer that doesn't actually hold any accessible memory,
     // use a null ByteBuffer
     *buf = NULL;
+
+    if (buffer == NULL) {
+        ALOGV("createByteBufferFromABuffer - given NULL, returning NULL");
+        return OK;
+    }
+
     if (buffer->base() == NULL) {
         return OK;
     }