Replace DeviceManager::GetDeviceChanges with a client interface.

device/usb/mojo/device_manager_impl.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 DEVICE_USB_MOJO_DEVICE_MANAGER_IMPL_H_
 #define DEVICE_USB_MOJO_DEVICE_MANAGER_IMPL_H_
 
 #include <memory>
 #include <queue>
 #include <set>
@@ skipping 35 matching lines @@
   ~DeviceManagerImpl() override;
 
   void set_connection_error_handler(const mojo::Closure& error_handler) {
     connection_error_handler_ = error_handler;
   }
 
  private:
   // DeviceManager implementation:
   void GetDevices(EnumerationOptionsPtr options,
                   const GetDevicesCallback& callback) override;
-  void GetDeviceChanges(const GetDeviceChangesCallback& callback) override;
   void GetDevice(const mojo::String& guid,
                  mojo::InterfaceRequest<Device> device_request) override;
+  void SetClient(DeviceManagerClientPtr client) override;
 
   // Callbacks to handle the async responses from the underlying UsbService.
   void OnGetDevices(EnumerationOptionsPtr options,
                     const GetDevicesCallback& callback,
                     const std::vector<scoped_refptr<UsbDevice>>& devices);
 
   // UsbService::Observer implementation:
   void OnDeviceAdded(scoped_refptr<UsbDevice> device) override;
   void OnDeviceRemoved(scoped_refptr<UsbDevice> device) override;
   void WillDestroyUsbService() override;
 
   void MaybeRunDeviceChangesCallback();
 
   base::WeakPtr<PermissionProvider> permission_provider_;
 
-  // If there are unfinished calls to GetDeviceChanges their callbacks
-  // are stored in |device_change_callbacks_|. Otherwise device changes
-  // are collected in |devices_added_| and |devices_removed_| until the
-  // next call to GetDeviceChanges.
-  std::queue<GetDeviceChangesCallback> device_change_callbacks_;
-  std::map<std::string, DeviceInfoPtr> devices_added_;
-  std::vector<DeviceInfoPtr> devices_removed_;
-
   UsbService* usb_service_;
   ScopedObserver<UsbService, UsbService::Observer> observer_;
+  DeviceManagerClientPtr client_;
 
   mojo::Closure connection_error_handler_;
 
   mojo::StrongBinding<DeviceManager> binding_;
   base::WeakPtrFactory<DeviceManagerImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceManagerImpl);
 };
 
 }  // namespace usb
 }  // namespace device
 
 #endif  // DEVICE_USB_MOJO_DEVICE_MANAGER_IMPL_H_