in shell/common/gin_converters/blink_converter.cc [117:149]
static bool FromV8(v8::Isolate* isolate,
v8::Handle<v8::Value> val,
blink::WebInputEvent::Modifiers* out) {
std::string modifier = base::ToLowerASCII(gin::V8ToString(isolate, val));
if (modifier == "shift")
*out = blink::WebInputEvent::Modifiers::kShiftKey;
else if (modifier == "control" || modifier == "ctrl")
*out = blink::WebInputEvent::Modifiers::kControlKey;
else if (modifier == "alt")
*out = blink::WebInputEvent::Modifiers::kAltKey;
else if (modifier == "meta" || modifier == "command" || modifier == "cmd")
*out = blink::WebInputEvent::Modifiers::kMetaKey;
else if (modifier == "iskeypad")
*out = blink::WebInputEvent::Modifiers::kIsKeyPad;
else if (modifier == "isautorepeat")
*out = blink::WebInputEvent::Modifiers::kIsAutoRepeat;
else if (modifier == "leftbuttondown")
*out = blink::WebInputEvent::Modifiers::kLeftButtonDown;
else if (modifier == "middlebuttondown")
*out = blink::WebInputEvent::Modifiers::kMiddleButtonDown;
else if (modifier == "rightbuttondown")
*out = blink::WebInputEvent::Modifiers::kRightButtonDown;
else if (modifier == "capslock")
*out = blink::WebInputEvent::Modifiers::kCapsLockOn;
else if (modifier == "numlock")
*out = blink::WebInputEvent::Modifiers::kNumLockOn;
else if (modifier == "left")
*out = blink::WebInputEvent::Modifiers::kIsLeft;
else if (modifier == "right")
*out = blink::WebInputEvent::Modifiers::kIsRight;
// TODO(nornagon): the rest of the modifiers
return true;
}