Use DCHECK_IS_ON() to determine if DCHECKs are enabled in InputHandlerProxy

We use NDEBUG for the condition to enable DCHECKs related to scroll
event sequence validity, but this doesn't consider that DCHECKs could be
enabled in release builds with dcheck_always_on.

Bug: 897791
Change-Id: I8bf894b9fcfd56d5c8256bafa4d00b3e1eb37ed2
Reviewed-on: https://chromium-review.googlesource.com/c/1348253Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610473}

ui/events/blink/input_handler_proxy.cc

@@ -144,7 +144,7 @@ InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler,
       input_handler_(input_handler),
       synchronous_input_handler_(nullptr),
       allow_root_animate_(true),
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
       expect_scroll_update_end_(false),
 #endif
       gesture_scroll_on_impl_thread_(false),
@@ -585,7 +585,7 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollBegin(
   if (compositor_event_queue_ && scroll_predictor_)
     scroll_predictor_->ResetOnGestureScrollBegin(gesture_event);
 
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   expect_scroll_update_end_ = true;
 #endif
   cc::ScrollState scroll_state = CreateScrollStateForGesture(gesture_event);
@@ -645,7 +645,7 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollBegin(
 InputHandlerProxy::EventDisposition
 InputHandlerProxy::HandleGestureScrollUpdate(
     const WebGestureEvent& gesture_event) {
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   DCHECK(expect_scroll_update_end_);
 #endif
 
@@ -696,7 +696,7 @@ InputHandlerProxy::HandleGestureScrollUpdate(
 
   if (snap_fling_controller_->HandleGestureScrollUpdate(
           GetGestureScrollUpdateInfo(gesture_event))) {
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
     expect_scroll_update_end_ = false;
 #endif
     gesture_scroll_on_impl_thread_ = false;
@@ -726,7 +726,7 @@ InputHandlerProxy::HandleGestureScrollUpdate(
 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollEnd(
   const WebGestureEvent& gesture_event) {
   TRACE_EVENT0("input", "InputHandlerProxy::HandleGestureScrollEnd");
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   DCHECK(expect_scroll_update_end_);
   expect_scroll_update_end_ = false;
 #endif

ui/events/blink/input_handler_proxy.h

@@ -186,7 +186,7 @@ class InputHandlerProxy : public cc::InputHandlerClient,
   SynchronousInputHandler* synchronous_input_handler_;
   bool allow_root_animate_;
 
-#ifndef NDEBUG
+#if DCHECK_IS_ON()
   bool expect_scroll_update_end_;
 #endif
   bool gesture_scroll_on_impl_thread_;