Drop ENABLE_NEW_GAMEPAD_API build flag as it is no longer needed

build/config/BUILD.gn

Index: build/config/BUILD.gn
diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index 21c54f9486c6fcb6a70cdb53b09b87025c9e8b9b..e0b2a2d8965033fa8791289a8789f8e335e40cc5 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -47,11 +47,6 @@ config("feature_flags") {
       "V8_DEPRECATION_WARNINGS",  # Don't use deprecated V8 APIs anywhere.
       # Temporary suppression until Blink code can be removed.
       "BLINK_SCALE_FILTERS_AT_RECORD_TIME",
-
-      # Enable a new Gamepad interface.
-      # TODO(cdumez): This is temporary and should go away once the chromium
-      # and blink interfaces are in sync, http://crbug.com/344556.
-      "ENABLE_NEW_GAMEPAD_API=1",
   ]
 
   if (cld_version > 0) {