Use shared memory for moving data over BlobChannel Mojo interface.

blimp/engine/mojo/blob_channel_service.h

Index: blimp/engine/mojo/blob_channel_service.h
diff --git a/blimp/engine/mojo/blob_channel_service.h b/blimp/engine/mojo/blob_channel_service.h
index 84e9623ab02af99f445f745b4fcf5b7edaf5ca87..5a983925238331beaeddf88817782a3edc3c38cc 100644
--- a/blimp/engine/mojo/blob_channel_service.h
+++ b/blimp/engine/mojo/blob_channel_service.h
@@ -31,7 +31,10 @@ class BlobChannelService : public mojom::BlobChannel {
                      mojom::BlobChannelRequest request);
 
   // BlobChannel implementation.
-  void PutBlob(const mojo::String& id, const mojo::String& data) override;
+  void PutBlob(const mojo::String& id,
+               mojo::ScopedSharedBufferHandle data,
+               uint32_t size,
+               const PutBlobCallback& callback) override;
   void DeliverBlob(const mojo::String& id) override;
 
   // Binds |this| and its object lifetime to a Mojo connection.