CdmAdapter: Report size of the file read by CDM via FileIO.

media/cdm/ppapi/cdm_adapter.h

Index: media/cdm/ppapi/cdm_adapter.h
diff --git a/media/cdm/ppapi/cdm_adapter.h b/media/cdm/ppapi/cdm_adapter.h
index c35fc4d7d20f17cf7b59222fdc7aad2b653cbfc3..98d38d36284f5af03ebbf2dd82d51e6043f31e21 100644
--- a/media/cdm/ppapi/cdm_adapter.h
+++ b/media/cdm/ppapi/cdm_adapter.h
@@ -247,6 +247,9 @@ class CdmAdapter : public pp::Instance,
 
   bool IsValidVideoFrame(const LinkedVideoFrame& video_frame);
 
+  // Callback to report |file_size_bytes| of the first file read by FileIO.
+  void OnFirstFileRead(int32_t file_size_bytes);
+
 #if !defined(NDEBUG)
   // Logs the given message to the JavaScript console associated with the
   // CDM adapter instance. The name of the CDM adapter issuing the log message
@@ -298,6 +301,9 @@ class CdmAdapter : public pp::Instance,
   bool deferred_initialize_video_decoder_;
   uint32_t deferred_video_decoder_config_id_;
 
+  uint32_t last_read_file_size_kb_;
+  bool file_size_uma_reported_;
+
   DISALLOW_COPY_AND_ASSIGN(CdmAdapter);
 };