[Device Service] Move Gamepad Blink headers to be part of the Gamepad client library

third_party/WebKit/Source/modules/gamepad/BUILD.gn

 # 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.
 
 import("//third_party/WebKit/Source/modules/modules.gni")
 
 blink_modules_sources("gamepad") {
   sources = [
     "Gamepad.cpp",
     "Gamepad.h",
     "GamepadButton.cpp",
     "GamepadButton.h",
     "GamepadDispatcher.cpp",
     "GamepadDispatcher.h",
     "GamepadEvent.cpp",
     "GamepadEvent.h",
     "GamepadList.cpp",
     "GamepadList.h",
     "GamepadPose.cpp",
     "GamepadPose.h",
     "NavigatorGamepad.cpp",
     "NavigatorGamepad.h",
   ]
+
+  deps = [
+    "//device/gamepad/public/cpp:shared_with_blink",
+  ]
 }