Refactor UKM interface for mojo-ification

ios/chrome/browser/application_context.h

Index: ios/chrome/browser/application_context.h
diff --git a/ios/chrome/browser/application_context.h b/ios/chrome/browser/application_context.h
index 0643826f8e87f12e6d14a8a3c69042d5cee93c51..d062e060b7eedd905de5c65e67855512313de2dc 100644
--- a/ios/chrome/browser/application_context.h
+++ b/ios/chrome/browser/application_context.h
@@ -50,7 +50,7 @@ class RapporServiceImpl;
 }
 
 namespace ukm {
-class UkmService;
+class UkmRecorder;
 }
 
 namespace variations {
@@ -103,8 +103,8 @@ class ApplicationContext {
   // Gets the MetricsService used by this application.
   virtual metrics::MetricsService* GetMetricsService() = 0;
 
-  // Gets the UkmService used by this application.
-  virtual ukm::UkmService* GetUkmService() = 0;
+  // Gets the UkmRecorder used by this application.
+  virtual ukm::UkmRecorder* GetUkmRecorder() = 0;
 
   // Gets the VariationsService used by this application.
   virtual variations::VariationsService* GetVariationsService() = 0;