Remove undefined declaration from RenderProcessHostImpl

Bug: 945167
Change-Id: Ida354c3fa5cd0076271fd76346122cf9bb17963d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1537101
Auto-Submit: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644419}

content/browser/renderer_host/render_process_host_impl.h

@@ -631,9 +631,6 @@ class CONTENT_EXPORT RenderProcessHostImpl
   static RenderProcessHost* FindReusableProcessHostForSiteInstance(
       SiteInstanceImpl* site_instance);
 
-  void CreateMediaStreamDispatcherHost(
-      MediaStreamManager* media_stream_manager,
-      blink::mojom::MediaStreamDispatcherHostRequest request);
   void CreateMediaStreamTrackMetricsHost(
       blink::mojom::MediaStreamTrackMetricsHostRequest request);