Add an Observer interface to UsbService for device add/remove.

extensions/browser/api/device_permissions_manager.h

Index: extensions/browser/api/device_permissions_manager.h
diff --git a/extensions/browser/api/device_permissions_manager.h b/extensions/browser/api/device_permissions_manager.h
index 647addc5fe1e7df0b1ac2a918b3534e9823ce8a4..52a1bd92b01aab7685a7712dd6fa1ebd82eed553 100644
--- a/extensions/browser/api/device_permissions_manager.h
+++ b/extensions/browser/api/device_permissions_manager.h
@@ -18,7 +18,7 @@
 #include "base/threading/thread_checker.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
-#include "device/usb/usb_device.h"
+#include "device/usb/usb_service.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/process_manager_observer.h"
 
@@ -33,10 +33,6 @@ namespace content {
 class BrowserContext;
 }
 
-namespace device {
-class UsbDevice;
-}
-
 namespace extensions {
 
 // Stores information about a device saved with access granted.
@@ -136,7 +132,7 @@ class DevicePermissions {
 class DevicePermissionsManager : public KeyedService,
                                  public base::NonThreadSafe,
                                  public ProcessManagerObserver,
-                                 public device::UsbDevice::Observer {
+                                 public device::UsbService::Observer {
  public:
   static DevicePermissionsManager* Get(content::BrowserContext* context);
 
@@ -184,13 +180,15 @@ class DevicePermissionsManager : public KeyedService,
   // ProcessManagerObserver implementation
   void OnBackgroundHostClose(const std::string& extension_id) override;
 
-  // device::UsbDevice::Observer implementation
-  void OnDisconnect(scoped_refptr<device::UsbDevice> device) override;
+  // device::UsbService::Observer implementation
+  void OnDeviceRemoved(scoped_refptr<device::UsbDevice> device) override;
 
   content::BrowserContext* context_;
   std::map<std::string, DevicePermissions*> extension_id_to_device_permissions_;
   ScopedObserver<ProcessManager, ProcessManagerObserver>
       process_manager_observer_;
+  ScopedObserver<device::UsbService, device::UsbService::Observer>
+      usb_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(DevicePermissionsManager);
 };