Rename "register" -> "subscribe" in the Push Messaging code.

content/shell/browser/layout_test/layout_test_push_messaging_service.h

Index: content/shell/browser/layout_test/layout_test_push_messaging_service.h
diff --git a/content/shell/browser/layout_test/layout_test_push_messaging_service.h b/content/shell/browser/layout_test/layout_test_push_messaging_service.h
index 1158963289e785c0f4f825ae363cfe6dded825ed..83b74c86624f88eb14798abbd134e32114bcdef4 100644
--- a/content/shell/browser/layout_test/layout_test_push_messaging_service.h
+++ b/content/shell/browser/layout_test/layout_test_push_messaging_service.h
@@ -21,28 +21,28 @@ class LayoutTestPushMessagingService : public PushMessagingService {
 
   // PushMessagingService implementation:
   GURL GetPushEndpoint() override;
-  void RegisterFromDocument(
+  void SubscribeFromDocument(
       const GURL& requesting_origin,
       int64 service_worker_registration_id,
       const std::string& sender_id,
       int renderer_id,
       int render_frame_id,
       bool user_visible,
-      const PushMessagingService::RegisterCallback& callback) override;
-  void RegisterFromWorker(
+      const PushMessagingService::SubscribeCallback& callback) override;
+  void SubscribeFromWorker(
       const GURL& requesting_origin,
       int64 service_worker_registration_id,
       const std::string& sender_id,
       bool user_visible,
-      const PushMessagingService::RegisterCallback& callback) override;
+      const PushMessagingService::SubscribeCallback& callback) override;
   blink::WebPushPermissionStatus GetPermissionStatus(
       const GURL& requesting_origin,
       const GURL& embedding_origin,
       bool user_visible) override;
-  void Unregister(const GURL& requesting_origin,
-                  int64 service_worker_registration_id,
-                  const std::string& sender_id,
-                  const UnregisterCallback& callback) override;
+  void Unsubscribe(const GURL& requesting_origin,
+                   int64 service_worker_registration_id,
+                   const std::string& sender_id,
+                   const UnsubscribeCallback& callback) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayoutTestPushMessagingService);