Remove unused GeolocationDispatcher::geolocationDestroyed().

As of Blink r180944, Blink is no longer notifying the embedder of its
GeolocationController reference going away (as there's no need.) Follow
up and retire the notification implementation on the embedder side.

R=mvanouwerkerk@chromium.org, jochen@chromium.org
BUG=

Review URL: https://codereview.chromium.org/526123002

Cr-Commit-Position: refs/heads/master@{#292890}

content/renderer/geolocation_dispatcher.cc

@@ -41,11 +41,6 @@ bool GeolocationDispatcher::OnMessageReceived(const IPC::Message& message) {
   return handled;
 }
 
-void GeolocationDispatcher::geolocationDestroyed() {
-  controller_.reset();
-  DCHECK(!updating_);
-}
-
 void GeolocationDispatcher::startUpdating() {
   GURL url;
   Send(new GeolocationHostMsg_StartUpdating(

content/renderer/geolocation_dispatcher.h

@@ -34,7 +34,6 @@ class GeolocationDispatcher : public RenderFrameObserver,
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // WebGeolocationClient
-  virtual void geolocationDestroyed();
   virtual void startUpdating();
   virtual void stopUpdating();
   virtual void setEnableHighAccuracy(bool enable_high_accuracy);
@@ -51,9 +50,6 @@ class GeolocationDispatcher : public RenderFrameObserver,
   // We have an updated geolocation position or error code.
   void OnPositionUpdated(const content::Geoposition& geoposition);
 
-  // The controller_ is valid for the lifetime of the underlying
-  // WebCore::GeolocationController. geolocationDestroyed() is
-  // invoked when the underlying object is destroyed.
   scoped_ptr<blink::WebGeolocationController> controller_;
 
   scoped_ptr<blink::WebGeolocationPermissionRequestManager>