Refactored gamepad polling to support dynamic sources

device/gamepad/gamepad_platform_data_fetcher_linux.h

Index: device/gamepad/gamepad_platform_data_fetcher_linux.h
diff --git a/device/gamepad/gamepad_platform_data_fetcher_linux.h b/device/gamepad/gamepad_platform_data_fetcher_linux.h
index 39907c9b6af48f14bdee8eeb5f3e396febb347e4..af45514c12152abab767d13b2585286b1ac37651 100644
--- a/device/gamepad/gamepad_platform_data_fetcher_linux.h
+++ b/device/gamepad/gamepad_platform_data_fetcher_linux.h
@@ -26,14 +26,21 @@ namespace device {
 
 class GamepadPlatformDataFetcherLinux : public GamepadDataFetcher {
  public:
+  typedef GamepadDataFetcherFactoryImpl<GamepadPlatformDataFetcherLinux,
+                                        GAMEPAD_SOURCE_LINUX_UDEV>
+      Factory;
+
   GamepadPlatformDataFetcherLinux();
   ~GamepadPlatformDataFetcherLinux() override;
 
+  GamepadSource source() override;
+
   // GamepadDataFetcher implementation.
-  void GetGamepadData(blink::WebGamepads* pads,
-                      bool devices_changed_hint) override;
+  void GetGamepadData(bool devices_changed_hint) override;
 
  private:
+  void OnAddedToProvider() override;
+
   void RefreshDevice(udev_device* dev);
   void EnumerateDevices();
   void ReadDeviceData(size_t index);