Make stylus's eraser button work on Mac

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 4bbf13f0be7f533b4700161c86e22e63c83846a8..c2083b27f1329925ffc66646ced19fc1ca4c01d0 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -1911,10 +1911,16 @@ void RenderWidgetHostViewMac::OnDisplayMetricsChanged(
   // Set the pointer type when we are receiving a NSMouseEntered event and the
   // following NSMouseExited event should have the same pointer type.
   NSEventType type = [theEvent type];
-  if (type == NSMouseEntered) {
+  if (type == NSMouseEntered || type == NSMouseExited) {
     pointerType_ = isStylusEnteringProximity_

[Navid Zolghadr, 2017/03/08 19:30:27]

Can we just use an if statement here and not set pointerType_ if stylus was not
in proximity?

[lanwei, 2017/03/08 21:01:19]

I thought it was clearer to set the pointer type for all cases in this class, so
we do not need to worry about it anymore.

-                       ? blink::WebPointerProperties::PointerType::Pen
+                       ? pointerType_
                        : blink::WebPointerProperties::PointerType::Mouse;
+  } else {
+    NSEventSubtype subtype = [theEvent subtype];
+    if (subtype != NSTabletPointEventSubtype &&
+        subtype != NSTabletProximityEventSubtype) {
+      pointerType_ = blink::WebPointerProperties::PointerType::Mouse;

[Navid Zolghadr, 2017/03/08 19:30:27]

Why did we make this change here along with the eraser pointertype? Is that
related?

[lanwei, 2017/03/08 21:01:19]

I moved all the logic of setting the pointer type here in this class.

+    }
   }
 
   if ([self shouldIgnoreMouseEvent:theEvent]) {
@@ -1987,8 +1993,13 @@ void RenderWidgetHostViewMac::OnDisplayMetricsChanged(
 }
 
 - (void)tabletEvent:(NSEvent*)theEvent {
-  if ([theEvent type] == NSTabletProximity)
+  if ([theEvent type] == NSTabletProximity) {
     isStylusEnteringProximity_ = [theEvent isEnteringProximity];
+    NSPointingDeviceType deviceType = [theEvent pointingDeviceType];
+    pointerType_ = deviceType == NSEraserPointingDevice
+                       ? blink::WebPointerProperties::PointerType::Eraser
+                       : blink::WebPointerProperties::PointerType::Pen;
+  }
 }
 
 - (BOOL)performKeyEquivalent:(NSEvent*)theEvent {