Extract shell methods from ApplicationImpl into a base class, and pass this to Initialize() instead.

components/html_viewer/stats_collection_controller.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_HTML_VIEWER_STATS_COLLECTION_CONTROLLER_H_
 #define COMPONENTS_HTML_VIEWER_STATS_COLLECTION_CONTROLLER_H_
 
 #include "base/macros.h"
 #include "gin/wrappable.h"
 #include "mojo/services/tracing/public/interfaces/tracing.mojom.h"
 
 namespace blink {
 class WebFrame;
 }
 
 namespace mojo {
-class ApplicationImpl;
+class Shell;
 }
 
 namespace html_viewer {
 
 // This class is exposed in JS as window.statsCollectionController and provides
 // functionality to read out statistics from the browser.
 // Its use must be enabled specifically via the
 // --enable-stats-collection-bindings command line flag.
 class StatsCollectionController
     : public gin::Wrappable<StatsCollectionController> {
  public:
   static gin::WrapperInfo kWrapperInfo;
 
   // Install the JS and return a mojo:tracing InterfacePtr for stats reporting.
   // This bails and returns a null pointer without the stats command line flag.
   static tracing::StartupPerformanceDataCollectorPtr Install(
       blink::WebFrame* frame,
-      mojo::ApplicationImpl* app);
+      mojo::Shell* shell);
 
   // Return a mojo:metrics InterfacePtr for stats reporting.
   // This bails and returns a null pointer without the stats command line flag.
   static tracing::StartupPerformanceDataCollectorPtr ConnectToDataCollector(
-      mojo::ApplicationImpl* app);
+      mojo::Shell* shell);
 
  private:
   explicit StatsCollectionController(
       tracing::StartupPerformanceDataCollectorPtr collector);
   ~StatsCollectionController() override;
 
   // gin::WrappableBase
   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
       v8::Isolate* isolate) override;
 
   // Retrieves a histogram and returns a JSON representation of it.
   std::string GetHistogram(const std::string& histogram_name);
 
   // Retrieves a browser histogram and returns a JSON representation of it.
   std::string GetBrowserHistogram(const std::string& histogram_name);
 
   tracing::StartupPerformanceDataCollectorPtr
       startup_performance_data_collector_;
 
   DISALLOW_COPY_AND_ASSIGN(StatsCollectionController);
 };
 
 }  // namespace html_viewer
 
 #endif  // COMPONENTS_HTML_VIEWER_STATS_COLLECTION_CONTROLLER_H_