Drop ENABLE_NEW_GAMEPAD_API build flag as it is no longer needed

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 95f1cbb889b3953fa4f68e239d11bef5b1f20967..e99c6ae5de292392148332df2a4e9bc58e815484 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -2288,11 +2288,6 @@
       # Targets are by default not nacl untrusted code.
       'nacl_untrusted_build%': 0,
 
-      # 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,
-
       'pnacl_compile_flags': [
         # pnacl uses the clang compiler so we need to suppress all the
         # same warnings as we do for clang.
@@ -2462,9 +2457,6 @@
       ['enable_hidpi==1', {
         'defines': ['ENABLE_HIDPI=1'],
       }],
-      ['enable_new_gamepad_api==1', {
-        'defines': ['ENABLE_NEW_GAMEPAD_API=1'],
-      }],
       ['native_discardable_memory==1', {
         'defines': ['DISCARDABLE_MEMORY_ALWAYS_SUPPORTED_NATIVELY'],
       }],