Expose loading state from Blimp to Tab

blimp/client/core/contents/blimp_navigation_controller_delegate.h

 // Copyright 2016 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 BLIMP_CLIENT_CORE_CONTENTS_BLIMP_NAVIGATION_CONTROLLER_DELEGATE_H_
 #define BLIMP_CLIENT_CORE_CONTENTS_BLIMP_NAVIGATION_CONTROLLER_DELEGATE_H_
 
 #include "base/macros.h"
 #include "url/gurl.h"
 
 namespace blimp {
 namespace client {
 
 // Interface for objects embedding a BlimpNavigationControllerImpl to provide
 // the functionality BlimpNavigationControllerImpl needs.
 class BlimpNavigationControllerDelegate {
  public:
   virtual ~BlimpNavigationControllerDelegate() = default;
 
+  // TODO(dtrainor): Pull apart this method into more fine grained notifications
+  // or add an enum to detect exactly which state changed.
   // Informs the delegate that navigation state has changed.
   virtual void OnNavigationStateChanged() = 0;
 
+  // Informs the delegate that navigation loading has started or stopped.
+  virtual void OnLoadingStateChanged(bool loading) = 0;
+
  protected:
   BlimpNavigationControllerDelegate() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BlimpNavigationControllerDelegate);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_CORE_CONTENTS_BLIMP_NAVIGATION_CONTROLLER_DELEGATE_H_