Refactored gamepad polling to support dynamic sources

device/gamepad/gamepad_test_helpers.h

Index: device/gamepad/gamepad_test_helpers.h
diff --git a/device/gamepad/gamepad_test_helpers.h b/device/gamepad/gamepad_test_helpers.h
index 7681bf9769458ebe1938f42901955bd05c0c9eca..4e482dc1b064e615d297a61aa32397480ae7acb5 100644
--- a/device/gamepad/gamepad_test_helpers.h
+++ b/device/gamepad/gamepad_test_helpers.h
@@ -28,9 +28,10 @@ class MockGamepadDataFetcher : public GamepadDataFetcher {
 
   ~MockGamepadDataFetcher() override;
 
+  GamepadSource source() override;
+
   // GamepadDataFetcher.
-  void GetGamepadData(blink::WebGamepads* pads,
-                      bool devices_changed_hint) override;
+  void GetGamepadData(bool devices_changed_hint) override;
 
   // Blocks the current thread until the GamepadProvider reads from this
   // fetcher on the background thread.