stagefright: untangle metadata-mode handling

- specify requested metadata mode from producers to OMX
- (pass requested metadata in IOMX::storeMetadataInBuffers)
- use correct logic for native handle source
- use native handle source for encoded meta buffers

Bug: 22775369
Change-Id: I58b03acd3e9a5367d5010d7f87b7af5cae23362c
diff --git a/include/media/IOMX.h b/include/media/IOMX.h
index 8caf72d..673c56a 100644
--- a/include/media/IOMX.h
+++ b/include/media/IOMX.h
@@ -276,17 +276,18 @@
     OMX_U32 mLevel;
 };
 
-}  // namespace android
-
-inline static const char *asString(android::MetadataBufferType i, const char *def = "??") {
+inline static const char *asString(MetadataBufferType i, const char *def = "??") {
     using namespace android;
     switch (i) {
         case kMetadataBufferTypeCameraSource:   return "CameraSource";
         case kMetadataBufferTypeGrallocSource:  return "GrallocSource";
         case kMetadataBufferTypeANWBuffer:      return "ANWBuffer";
+        case kMetadataBufferTypeNativeHandleSource: return "NativeHandleSource";
         case kMetadataBufferTypeInvalid:        return "Invalid";
         default:                                return def;
     }
 }
 
+}  // namespace android
+
 #endif  // ANDROID_IOMX_H_