Refactored gamepad polling to support dynamic sources

device/gamepad/BUILD.gn

Index: device/gamepad/BUILD.gn
diff --git a/device/gamepad/BUILD.gn b/device/gamepad/BUILD.gn
index 7c0d6695acfa00d1eb5250e9c40f0e4e149b8490..ef6b7a83291139daca540aef812ebef96b27b44b 100644
--- a/device/gamepad/BUILD.gn
+++ b/device/gamepad/BUILD.gn
@@ -17,6 +17,8 @@ component("gamepad") {
     "gamepad_consumer.h",
     "gamepad_data_fetcher.cc",
     "gamepad_data_fetcher.h",
+    "gamepad_data_fetcher_manager.cc",
+    "gamepad_data_fetcher_manager.h",
     "gamepad_platform_data_fetcher.h",
     "gamepad_platform_data_fetcher_android.cc",
     "gamepad_platform_data_fetcher_android.h",
@@ -37,8 +39,8 @@ component("gamepad") {
     "gamepad_user_gesture.h",
     "raw_input_data_fetcher_win.cc",
     "raw_input_data_fetcher_win.h",
-    "xbox_data_fetcher_mac.cc",
     "xbox_data_fetcher_mac.h",
+    "xbox_data_fetcher_mac.mm",
   ]
 
   deps = [
@@ -56,7 +58,6 @@ component("gamepad") {
   if (is_linux && use_udev) {
     deps += [ "//device/udev_linux" ]
   } else if (!is_win && !is_mac && !is_android) {
-    sources += [ "gamepad_platform_data_fetcher.cc" ]
     sources -= [ "gamepad_platform_data_fetcher_linux.cc" ]
   }