Remove unused/unimplemented UpdateEventRectsForSubframeIfNecessary().

R=dcheng

Bug: 912193
Change-Id: Ic61fec531ad323dfe174930deb9dc9ec64c46b4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1713704
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#679928}

third_party/blink/public/platform/web_layer_tree_view.h

@@ -74,7 +74,6 @@ class WebLayerTreeView {
   virtual void ForceRecalculateRasterScales() {}
 
   // Input properties ---------------------------------------------------
-  virtual void UpdateEventRectsForSubframeIfNecessary() {}
   virtual void SetHaveScrollEventHandlers(bool) {}
 
   // Returns the FrameSinkId of the widget associated with this layer tree view.