Provide access to the WindowEventDispatcher as a ui::EventProcessor.

ui/snapshot/snapshot_aura_unittest.cc

Index: ui/snapshot/snapshot_aura_unittest.cc
diff --git a/ui/snapshot/snapshot_aura_unittest.cc b/ui/snapshot/snapshot_aura_unittest.cc
index 257f8548e9ea7285671f752356502ced8ee794a3..b000ad1cd75c774c747c24873752cf6894c6c58a 100644
--- a/ui/snapshot/snapshot_aura_unittest.cc
+++ b/ui/snapshot/snapshot_aura_unittest.cc
@@ -107,12 +107,11 @@ class SnapshotAuraTest : public testing::Test {
  protected:
   aura::Window* test_window() { return test_window_.get(); }
   aura::Window* root_window() { return helper_->root_window(); }
-  aura::WindowEventDispatcher* dispatcher() { return helper_->dispatcher(); }
   aura::TestScreen* test_screen() { return helper_->test_screen(); }
 
   void WaitForDraw() {
-    dispatcher()->host()->compositor()->ScheduleDraw();
-    ui::DrawWaiterForTest::Wait(dispatcher()->host()->compositor());
+    helper_->host()->compositor()->ScheduleDraw();
+    ui::DrawWaiterForTest::Wait(helper_->host()->compositor());
   }
 
   void SetupTestWindow(const gfx::Rect& window_bounds) {