Updating Gamepad API to match latest spec

ppapi/shared_impl/ppb_gamepad_shared.h

Index: ppapi/shared_impl/ppb_gamepad_shared.h
diff --git a/ppapi/shared_impl/ppb_gamepad_shared.h b/ppapi/shared_impl/ppb_gamepad_shared.h
index 821980f3aa72ef676d92402cce581d5aa4507438..75f8b445a8c72c93011406ced7b001d8ba7a3bb8 100644
--- a/ppapi/shared_impl/ppb_gamepad_shared.h
+++ b/ppapi/shared_impl/ppb_gamepad_shared.h
@@ -21,6 +21,7 @@ namespace ppapi {
 // has some compile asserts to validate this.
 struct WebKitGamepad {
     static const size_t kIdLengthCap = 128;
+    static const size_t kMappingLengthCap = 16;
     static const size_t kAxesLengthCap = 16;
     static const size_t kButtonsLengthCap = 32;
 
@@ -30,6 +31,11 @@ struct WebKitGamepad {
     // Device identifier (based on manufacturer, model, etc.).
     base::char16 id[kIdLengthCap];
 
+#ifdef ENABLE_NEW_GAMEPAD_API
+    // Mapping type (for example "standard")
+    base::char16 mapping[kMappingLengthCap];
+#endif
+
     // Monotonically increasing value referring to when the data were last
     // updated.
     unsigned long long timestamp;