Remove invalid pinch-zoom assert in top_controls_manager

cc/input/top_controls_manager.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 "cc/input/top_controls_manager.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 
@@ skipping 77 matching lines @@
 
   if (animate) {
     SetupAnimation(final_shown_ratio ? SHOWING_CONTROLS : HIDING_CONTROLS);
   } else {
     ResetAnimations();
     client_->SetCurrentTopControlsShownRatio(final_shown_ratio);
   }
 }
 
 void TopControlsManager::ScrollBegin() {
-  DCHECK(!pinch_gesture_active_);
+  if (pinch_gesture_active_)
+    return;
+
   ResetAnimations();
   ResetBaseline();
 }
 
 gfx::Vector2dF TopControlsManager::ScrollBy(
     const gfx::Vector2dF& pending_delta) {
   if (!TopControlsHeight())
     return pending_delta;
 
   if (pinch_gesture_active_)
@@ skipping 16 matching lines @@
   if (TopControlsShownRatio() == 1.f)
     ResetBaseline();
 
   ResetAnimations();
 
   gfx::Vector2dF applied_delta(0.f, old_offset - ContentTopOffset());
   return pending_delta - applied_delta;
 }
 
 void TopControlsManager::ScrollEnd() {
-  DCHECK(!pinch_gesture_active_);
+  if (pinch_gesture_active_)
+    return;
+
   StartAnimationIfNecessary();
 }
 
 void TopControlsManager::PinchBegin() {
   DCHECK(!pinch_gesture_active_);
   pinch_gesture_active_ = true;
   StartAnimationIfNecessary();
 }
 
 void TopControlsManager::PinchEnd() {
@@ skipping 80 matching lines @@
   return (animation_direction_ == SHOWING_CONTROLS && new_ratio >= 1.f) ||
          (animation_direction_ == HIDING_CONTROLS && new_ratio <= 0.f);
 }
 
 void TopControlsManager::ResetBaseline() {
   accumulated_scroll_delta_ = 0.f;
   baseline_content_offset_ = ContentTopOffset();
 }
 
 }  // namespace cc