Introduce EventProcessor::OnEventProcessingStarted()

ui/events/test/test_event_processor.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_EVENTS_TEST_TEST_EVENT_PROCESSOR_H_
 #define UI_EVENTS_TEST_TEST_EVENT_PROCESSOR_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/events/event_processor.h"
 
 namespace ui {
 namespace test {
 
 class TestEventProcessor : public EventProcessor {
  public:
   TestEventProcessor();
   virtual ~TestEventProcessor();
 
+  int num_times_processing_started() const {
+    return num_times_processing_started_;
+  }
+
   int num_times_processing_finished() const {
     return num_times_processing_finished_;
   }
 
   void SetRoot(scoped_ptr<EventTarget> root);
-  void ResetCounts();
+  void SetShouldProcessingOccur(bool occur);
+  void Reset();
 
   // EventProcessor:
   virtual bool CanDispatchToTarget(EventTarget* target) OVERRIDE;
   virtual EventTarget* GetRootTarget() OVERRIDE;
   virtual EventDispatchDetails OnEventFromSource(Event* event) OVERRIDE;
+  virtual void OnEventProcessingStarted(Event* event) OVERRIDE;
   virtual void OnEventProcessingFinished(Event* event) OVERRIDE;
 
  private:
   scoped_ptr<EventTarget> root_;
 
+  // Used in our override of OnEventProcessingStarted(). If this value is
+  // false, mark incoming events as handled.
+  bool should_processing_occur_;
+
+  // Counts the number of times OnEventProcessingStarted() has been called.
+  int num_times_processing_started_;
+
   // Counts the number of times OnEventProcessingFinished() has been called.
   int num_times_processing_finished_;
 
   DISALLOW_COPY_AND_ASSIGN(TestEventProcessor);
 };
 
 }  // namespace test
 }  // namespace ui
 
 #endif  // UI_EVENTS_TEST_TEST_EVENT_PROCESSOR_H_