Simpified Gesture Nav: Don't navigate if affordance isn't showing.

content/browser/web_contents/aura/gesture_nav_simple.cc

 // Copyright 2014 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 "content/browser/web_contents/aura/gesture_nav_simple.h"
 
 #include <utility>
 
 #include "base/macros.h"
 #include "cc/paint/paint_flags.h"
@@ skipping 367 matching lines @@
 
 bool GestureNavSimple::OnOverscrollUpdate(float delta_x, float delta_y) {
   if (!affordance_ || affordance_->IsFinishing())
     return false;
   affordance_->SetDragProgress(
       std::min(1.f, std::abs(delta_x) / completion_threshold_));
   return true;
 }
 
 void GestureNavSimple::OnOverscrollComplete(OverscrollMode overscroll_mode) {
+  if (!affordance_ || affordance_->IsFinishing())
+    return;
+
   CompleteGestureAnimation();
 
   NavigationControllerImpl& controller = web_contents_->GetController();
   if (ShouldNavigateForward(controller, overscroll_mode))
     controller.GoForward();
   else if (ShouldNavigateBack(controller, overscroll_mode))
     controller.GoBack();
 }
 
 void GestureNavSimple::OnOverscrollModeChange(OverscrollMode old_mode,
@@ skipping 12 matching lines @@
           ? OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHPAD
           : OVERSCROLL_CONFIG_HORIZ_THRESHOLD_START_TOUCHSCREEN);
   const int width = source == OverscrollSource::TOUCHPAD
                         ? GetDisplaySize().width()
                         : GetVisibleSize().width();
   completion_threshold_ =
       width * GetOverscrollConfig(OVERSCROLL_CONFIG_HORIZ_THRESHOLD_COMPLETE) -
       start_threshold;
 
   aura::Window* window = web_contents_->GetNativeView();
-  affordance_.reset(new Affordance(this, new_mode, window->bounds()));
+  affordance_ = base::MakeUnique<Affordance>(this, new_mode, window->bounds());
 
   // Adding the affordance as a child of the content window is not sufficient,
   // because it is possible for a new layer to be parented on top of the
   // affordance layer (e.g. when the navigated-to page is displayed while the
   // completion animation is in progress). So instead, it is installed on top of
   // the content window as its sibling. Note that the affordance itself makes
   // sure that its contents are clipped to the bounds given to it.
   ui::Layer* parent = window->layer()->parent();
   parent->Add(affordance_->root_layer());
   parent->StackAtTop(affordance_->root_layer());
 }
 
 base::Optional<float> GestureNavSimple::GetMaxOverscrollDelta() const {
   if (affordance_)
     return completion_threshold_;
   return base::nullopt;
 }
 
 }  // namespace content