[chromecast] Fix build with enable_mojo_media=true.

chromecast/browser/media/cast_mojo_media_client.h

Index: chromecast/browser/media/cast_mojo_media_client.h
diff --git a/chromecast/browser/media/cast_mojo_media_client.h b/chromecast/browser/media/cast_mojo_media_client.h
index 504d71371f4a6383c2d078b43bb13a2502c214e9..9dcd6affb412d1d5ffb15c05818d8852a2eb085c 100644
--- a/chromecast/browser/media/cast_mojo_media_client.h
+++ b/chromecast/browser/media/cast_mojo_media_client.h
@@ -5,16 +5,15 @@
 #ifndef CHROMECAST_BROWSER_MEDIA_CAST_MOJO_MEDIA_CLIENT_H_
 #define CHROMECAST_BROWSER_MEDIA_CAST_MOJO_MEDIA_CLIENT_H_
 
+#include "chromecast/browser/media/media_pipeline_backend_factory.h"
 #include "media/mojo/services/mojo_media_client.h"
 
 namespace chromecast {
 namespace media {
 
-class CmaMediaPipelineClient;
-
 class CastMojoMediaClient : public ::media::MojoMediaClient {
  public:
-  CastMojoMediaClient(scoped_refptr<CmaMediaPipelineClient> pipeline_client);
+  CastMojoMediaClient(const CreateMediaPipelineBackendCB& create_backend_cb);
   ~CastMojoMediaClient() override;
 
   // MojoMediaClient overrides.
@@ -22,7 +21,7 @@ class CastMojoMediaClient : public ::media::MojoMediaClient {
       const scoped_refptr<::media::MediaLog>& media_log) override;
 
  private:
-  scoped_refptr<CmaMediaPipelineClient> pipeline_client_;
+  const CreateMediaPipelineBackendCB create_backend_cb_;
   DISALLOW_COPY_AND_ASSIGN(CastMojoMediaClient);
 };