Fix overscroll getting kicked in on non-precise wheel scrolls

content/browser/renderer_host/overscroll_controller.cc

 // Copyright (c) 2012 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/renderer_host/overscroll_controller.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "content/browser/renderer_host/overscroll_controller_delegate.h"
 #include "content/public/browser/overscroll_configuration.h"
@@ skipping 32 matching lines @@
 bool OverscrollController::ShouldProcessEvent(
     const blink::WebInputEvent& event) {
     switch (event.type) {
       case blink::WebInputEvent::MouseWheel:
         return false;
       case blink::WebInputEvent::GestureScrollBegin:
       case blink::WebInputEvent::GestureScrollUpdate:
       case blink::WebInputEvent::GestureScrollEnd: {
         const blink::WebGestureEvent& gesture =
             static_cast<const blink::WebGestureEvent&>(event);
-        if (gesture.sourceDevice == blink::WebGestureDeviceTouchpad)
+        if (gesture.sourceDevice == blink::WebGestureDeviceTouchscreen)
           return true;

[sadrul, 2016/09/21 03:33:17]

Do you even need this special case here? Would the following not work for both
touchscreen and touchpad scrolls?

         blink::WebGestureEvent::ScrollUnits scrollUnits;
         switch (event.type) {
           case blink::WebInputEvent::GestureScrollBegin:
             scrollUnits = gesture.data.scrollBegin.deltaHintUnits;
             break;
           case blink::WebInputEvent::GestureScrollUpdate:
             scrollUnits = gesture.data.scrollUpdate.deltaUnits;
             break;
           case blink::WebInputEvent::GestureScrollEnd:
             scrollUnits = gesture.data.scrollEnd.deltaUnits;
@@ skipping 355 matching lines @@
   overscroll_mode_ = mode;
   if (overscroll_mode_ == OVERSCROLL_NONE)
     overscroll_delta_x_ = overscroll_delta_y_ = 0.f;
   else
     scroll_state_ = STATE_OVERSCROLLING;
   if (delegate_)
     delegate_->OnOverscrollModeChange(old_mode, overscroll_mode_);
 }
 
 }  // namespace content