Remove unnecessary DCHECK in TouchEventQueue handler notification

content/browser/renderer_host/input/touch_event_queue_unittest.cc

 // 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.
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "content/browser/renderer_host/input/timeout_monitor.h"
 #include "content/browser/renderer_host/input/touch_event_queue.h"
@@ skipping 370 matching lines @@
   MoveTouchPoint(0, 5, 5);
   EXPECT_EQ(2U, queued_event_count());
   EXPECT_EQ(0U, GetAndResetAckedEventCount());
   EXPECT_EQ(0U, GetAndResetSentEventCount());
 
   // Unregister all touch handlers.
   OnHasTouchEventHandlers(false);
   EXPECT_EQ(0U, GetAndResetAckedEventCount());
   EXPECT_EQ(2U, queued_event_count());
 
+  // Repeated registration/unregstration of handlers should have no effect as
+  // we're still awaiting the ack arrival.
+  OnHasTouchEventHandlers(true);
+  EXPECT_EQ(0U, GetAndResetAckedEventCount());
+  EXPECT_EQ(2U, queued_event_count());
+  OnHasTouchEventHandlers(false);
+  EXPECT_EQ(0U, GetAndResetAckedEventCount());
+  EXPECT_EQ(2U, queued_event_count());
+
   // The ack should be flush the queue.
   SendTouchEventAck(INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
   EXPECT_EQ(2U, GetAndResetAckedEventCount());
   EXPECT_EQ(0U, queued_event_count());
 
   // Events should be dropped while there is no touch handler.
   MoveTouchPoint(0, 10, 10);
   EXPECT_EQ(0U, queued_event_count());
   EXPECT_EQ(1U, GetAndResetAckedEventCount());
   EXPECT_EQ(0U, GetAndResetSentEventCount());
@@ skipping 1715 matching lines @@
   EXPECT_EQ(1U, GetAndResetSentEventCount());
 
   // Touch move event is throttled.
   MoveTouchPoint(0, 60, 5);
   SendTouchEventAck(INPUT_EVENT_ACK_STATE_CONSUMED);
   EXPECT_EQ(0U, queued_event_count());
   EXPECT_EQ(0U, GetAndResetSentEventCount());
 }
 
 }  // namespace content