Send pointerleave and pointerenter events for styluses on Mac

ui/base/cocoa/base_view.mm

Index: ui/base/cocoa/base_view.mm
diff --git a/ui/base/cocoa/base_view.mm b/ui/base/cocoa/base_view.mm
index 47ccca96ad6dd866b986183dbbec4db376f85be6..2172fec62acf67a7320b591ac6c6b2f5f7b25228 100644
--- a/ui/base/cocoa/base_view.mm
+++ b/ui/base/cocoa/base_view.mm
@@ -82,6 +82,10 @@ NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
   // This method left intentionally blank.
 }
 
+- (void)tabletEvent:(NSEvent*)theEvent {
+  // This method left intentionally blank.
+}
+
 - (void)mouseDown:(NSEvent*)theEvent {
   dragging_ = YES;
   [self mouseEvent:theEvent];
@@ -200,4 +204,8 @@ NSString* kSelectionDirection = @"Chromium.kSelectionDirection";
   return new_rect;
 }
 
+- (void)tabletProximity:(NSEvent*)theEvent {
+  [self tabletEvent:theEvent];
+}
+
 @end