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 1a6451c14ba29d531be6bdd78f94f68dd9e84876..26feb1d1b30fcf2e0595bcee38b415f1676bf361 100644
--- a/components/exo/BUILD.gn
+++ b/components/exo/BUILD.gn
@@ -11,6 +11,8 @@ source_set("exo") {
     "buffer.h",
     "display.cc",
     "display.h",
+    "gamepad.cc",
+    "gamepad.h",
     "keyboard.cc",
     "keyboard.h",
     "keyboard_delegate.h",
@@ -41,6 +43,7 @@ source_set("exo") {
     "//base",
     "//cc",
     "//cc/surfaces:surfaces",
+    "//device/gamepad",
     "//gpu",
     "//gpu/command_buffer/client:gles2_interface",
     "//skia",
@@ -83,6 +86,7 @@ source_set("unit_tests") {
   sources = [
     "buffer_unittest.cc",
     "display_unittest.cc",
+    "gamepad_unittest.cc",
     "keyboard_unittest.cc",
     "pointer_unittest.cc",
     "shared_memory_unittest.cc",
@@ -129,6 +133,7 @@ test("exo_unittests") {
     "//ash:test_support",
     "//base",
     "//base/test:test_support",
+    "//device/gamepad:test_helpers",
   ]
 
   data_deps = [