Apply Ash's key rewriter to an aura::MouseEvent so that Modifler+Click is handled correctly

ash/wm/key_rewriter_event_filter.cc

Index: ash/wm/key_rewriter_event_filter.cc
diff --git a/ash/wm/key_rewriter_event_filter.cc b/ash/wm/key_rewriter_event_filter.cc
index 30ba84da34db0b3bda5e4d74da55a37547909a5d..6e7ca2eb6f8a1ea310aef3ecda5dbeaca39b455e 100644
--- a/ash/wm/key_rewriter_event_filter.cc
+++ b/ash/wm/key_rewriter_event_filter.cc
@@ -44,7 +44,18 @@ bool KeyRewriterEventFilter::PreHandleKeyEvent(
 
 bool KeyRewriterEventFilter::PreHandleMouseEvent(
     aura::Window* target, aura::MouseEvent* event) {
-  return false;  // Not handled.
+  if (!delegate_.get())
+    return false;
+
+  switch (delegate_->RewriteOrFilterLocatedEvent(event)) {
+    case KeyRewriterDelegate::ACTION_REWRITE_EVENT:
+      return false;
+    case KeyRewriterDelegate::ACTION_DROP_EVENT:
+      return true;
+  }
+
+  NOTREACHED();
+  return false;
 }
 
 ui::TouchStatus KeyRewriterEventFilter::PreHandleTouchEvent(