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

media/cdm/ppapi/cdm_file_io_impl.h

Index: media/cdm/ppapi/cdm_file_io_impl.h
diff --git a/media/cdm/ppapi/cdm_file_io_impl.h b/media/cdm/ppapi/cdm_file_io_impl.h
index fc8215a17a863850f3fbd5bfd2e30a99c248c8e6..f8a78e5f35426816201c65d1693103db231390e0 100644
--- a/media/cdm/ppapi/cdm_file_io_impl.h
+++ b/media/cdm/ppapi/cdm_file_io_impl.h
@@ -35,7 +35,12 @@ class CdmFileIOImpl : public cdm::FileIO {
     DISALLOW_COPY_AND_ASSIGN(ResourceTracker);
   };
 
-  CdmFileIOImpl(cdm::FileIOClient* client, PP_Instance pp_instance);
+  // After the first successful file read, call |first_file_read_cb| to report
+  // the file size. |first_file_read_cb| takes one parameter: the file size in
+  // bytes.
+  CdmFileIOImpl(cdm::FileIOClient* client,
+                PP_Instance pp_instance,
+                const pp::CompletionCallback& first_file_read_cb);
 
   // cdm::FileIO implementation.
   virtual void Open(const char* file_name, uint32_t file_name_size) OVERRIDE;
@@ -158,6 +163,11 @@ class CdmFileIOImpl : public cdm::FileIO {
   // when read completes.
   std::vector<char> cumulative_read_buffer_;
 
+  bool first_file_read_reported_;
+
+  // Callback to report the file size in bytes after the first successful read.
+  pp::CompletionCallback first_file_read_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(CdmFileIOImpl);
 };