Add tangentialPressure and twist properties to PointerEvent on Mac

content/browser/renderer_host/input/web_input_event_builders_mac.mm

Index: content/browser/renderer_host/input/web_input_event_builders_mac.mm
diff --git a/content/browser/renderer_host/input/web_input_event_builders_mac.mm b/content/browser/renderer_host/input/web_input_event_builders_mac.mm
index 41a9d27b9d5356adfefeacef9ac57cbed7e64775..88d251b8e3e1c5b6151aa0986419b5f8734ba633 100644
--- a/content/browser/renderer_host/input/web_input_event_builders_mac.mm
+++ b/content/browser/renderer_host/input/web_input_event_builders_mac.mm
@@ -347,6 +347,8 @@ blink::WebMouseEvent WebMouseEventBuilder::Build(NSEvent* event, NSView* view) {
     NSPoint tilt = [event tilt];
     result.tiltX = lround(tilt.x * 90);
     result.tiltY = lround(tilt.y * 90);
+    result.tangentialPressure = [event tangentialPressure];
+    result.twist = [event rotation];

[mustaq, 2017/01/03 19:09:24]

The NSEvent spec doesn't specify the range at all, so we have to be careful
here:
https://developer.apple.com/reference/appkit/nsevent/1526249-rotation

Let's clamp NSEvent.rotation values within [0,360), including for negative
values.

Curious: did you see [0,359] in practice?

[lanwei, 2017/01/05 16:13:40]

Done. Yes, the value I saw is in this range.

   }
   return result;
 }