exo: Implement wayland gamepad support

components/exo/BUILD.gn

Index: components/exo/BUILD.gn
diff --git a/components/exo/BUILD.gn b/components/exo/BUILD.gn
index 26b75c8ef622cccbd521d52792a2d5aec1fd0961..9bc80f91ed7aee85b188a7dfd54803907fafb0d5 100644
--- a/components/exo/BUILD.gn
+++ b/components/exo/BUILD.gn
@@ -11,6 +11,8 @@ source_set("exo") {
     "buffer.h",
     "display.cc",
     "display.h",
+    "gamepads.cc",
+    "gamepads.h",
     "keyboard.cc",
     "keyboard.h",
     "keyboard_delegate.h",
@@ -38,6 +40,7 @@ source_set("exo") {
     "//base",
     "//cc",
     "//cc/surfaces:surfaces",
+    "//device/gamepad",
     "//gpu",
     "//gpu/command_buffer/client:gles2_interface",
     "//skia",
@@ -80,6 +83,7 @@ source_set("unit_tests") {
   sources = [
     "buffer_unittest.cc",
     "display_unittest.cc",
+    "gamepads_unittest.cc",
     "keyboard_unittest.cc",
     "pointer_unittest.cc",
     "shared_memory_unittest.cc",
@@ -124,6 +128,7 @@ test("exo_unittests") {
     "//ash:test_support",
     "//base",
     "//base/test:test_support",
+    "//device/gamepad:test_helpers",
   ]
   if (is_linux) {
     deps += [ "//components/exo/wayland:unit_tests" ]