Fix a few potential crashes

Change-Id: Icb71cb07495406be756e195f2578b6e3aa8b1163
diff --git a/media/ndk/NdkMediaFormat.cpp b/media/ndk/NdkMediaFormat.cpp
index a354d58..5598d5d 100644
--- a/media/ndk/NdkMediaFormat.cpp
+++ b/media/ndk/NdkMediaFormat.cpp
@@ -46,6 +46,10 @@
     ALOGV("private ctor");
     AMediaFormat* mData = new AMediaFormat();
     mData->mFormat = *((sp<AMessage>*)data);
+    if (mData->mFormat == NULL) {
+        ALOGW("got NULL format");
+        mData->mFormat = new AMessage;
+    }
     return mData;
 }