Revert "Send GSB before switching to mainthread scrolling in smooth scroll path."

This reverts commit 5d5a062f.

Reason for revert: added a failing test https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Win10/32246 see issue 822386

bug: 822386

Original change's description:
> Send GSB before switching to mainthread scrolling in smooth scroll path.
> 
> This cl is the equivalent of https://codereview.chromium.org/2854683002 fix for smooth scrolling
> path,if the compositor handles the GSB and during the scrolling we have to switch to main thread
> since the compositor cannot handle a GSU a GSB must be sent to the main thread since the original
> GSB was handled on the compositor rather than being sent to the main thread.
> 
> touchpad-scroll-impl-to-main.html is the test that forces switch from compositor thread to main
> thread in the middle of scrolling. It used to get executed with --disable-smooth-scrolling
> in this cl I've moved the test to a new virtual test suite that has default scroll animation
> value.
> 
> I have removed the test expectations since I have changed the test and this might fix the flake.
> 
> subpixel-accumulation.html needs scroll animation to be disabled and that's why I had to move it to
> a new test suite.
> 
> Bug: 820979, 708499, 757165, 800840
> Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
> Change-Id: I21b1f4285897d74559f6827e6a232f007dc897b0
> Reviewed-on: https://chromium-review.googlesource.com/961264
> Commit-Queue: Sahel Sharifymoghaddam <sahel@chromium.org>
> Reviewed-by: Timothy Dresser <tdresser@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#543425}

TBR=tdresser@chromium.org,sahel@chromium.org

Change-Id: I3c5253d96d011c9723063effac91c969ee352305
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 820979, 708499, 757165, 800840
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Reviewed-on: https://chromium-review.googlesource.com/963388Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543467}

third_party/WebKit/LayoutTests/FlagExpectations/disable-blink-features=RootLayerScrolling

@@ -2704,6 +2704,9 @@ crbug.com/749738 [ Win7 Debug ] http/tests/devtools/editor/text-editor-word-jump
 # Sheriff failures 2017-07-28
 crbug.com/749738 [ Win7 Debug ] http/tests/devtools/console/console-format-es6-2.js [ Timeout ]
 
+# Sheriff failure 2017-08-07
+crbug.com/708499 [ Linux ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Failure Pass ]
+
 # Sheriff failure 2017-08-29
 crbug.com/727252 [ Win7 ] external/wpt/media-source/mediasource-endofstream.html [ Pass Timeout ]
 
@@ -2887,6 +2890,7 @@ crbug.com/757165 [ Win ] paint/invalidation/scroll/scrollbar-damage-and-full-vie
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-filter-modified-save-restore.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-filter-modified.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/threaded/animations/svg/animated-filter-svg-element.html [ Skip ]
+crbug.com/757165 [ Win ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-clipping.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-color-over-color.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-color-over-gradient.html [ Skip ]
@@ -3186,6 +3190,9 @@ crbug.com/799814 [ Android ] fast/beacon/beacon-basic.html [ Pass Failure ]
 # This test has been flaky for some time on Win 7 (dgb)
 crbug.com/800078 [ Win7 ] http/tests/devtools/console/console-link-to-snippet.js [ Pass Failure ]
 
+# This test is flaking (failing, crashing) on mac_chromium_rel_ng.
+crbug.com/800840 [ Mac ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Skip ]
+
 # Sheriff failures 2018-01-19
 # This test is failing regularly on Win 7 (dgb), WebKit Mac10.11 (dgb),
 # WebKit Linux Trusty (dbg).

third_party/WebKit/LayoutTests/FlagExpectations/enable-slimming-paint-v2

@@ -1061,7 +1061,7 @@ crbug.com/778875 virtual/threaded/fast/animationworklet/animation-worklet-scroll
 crbug.com/692310 virtual/threaded/animations/composited-animations-rotate-zero-degrees.html [ Pass Failure Timeout ]
 
 # This test uses internal call to initiate smooth scrolling on impl-thread.
-crbug.com/667946 fast/compositor-wheel-scroll-latching/animated-scroll/touchpad-scroll-impl-to-main.html [ Failure ]
+crbug.com/667946 fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Failure ]
 
 
 # virtual/threaded variants of sub-directories and tests already skipped or marked as failing above.

third_party/WebKit/LayoutTests/TestExpectations

@@ -2763,6 +2763,9 @@ crbug.com/749738 [ Win7 Debug ] http/tests/devtools/editor/text-editor-word-jump
 # Sheriff failures 2017-08-04
 crbug.com/626703 [ Win7 Release ] external/wpt/html/semantics/tabular-data/processing-model-1/span-limits.html [ Timeout ]
 
+# Sheriff failure 2017-08-07
+crbug.com/708499 [ Linux ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Failure Pass ]
+
 crbug.com/731018 [ Mac ] sensor/accelerometer.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/ambient-light-sensor.html [ Failure Pass Crash ]
 crbug.com/731018 [ Mac ] sensor/gyroscope.html [ Failure Pass Crash ]
@@ -2944,6 +2947,7 @@ crbug.com/757165 [ Win ] paint/invalidation/scroll/scrollbar-damage-and-full-vie
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-filter-modified-save-restore.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-filter-modified.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/threaded/animations/svg/animated-filter-svg-element.html [ Skip ]
+crbug.com/757165 [ Win ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-clipping.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-color-over-color.html [ Skip ]
 crbug.com/757165 [ Win ] virtual/gpu/fast/canvas/canvas-blending-color-over-gradient.html [ Skip ]
@@ -3242,6 +3246,9 @@ crbug.com/798680 external/wpt/pointerevents/pointerlock/pointerevent_pointerlock
 crbug.com/804682 [ Mac ] external/wpt/service-workers/service-worker/navigation-preload/resource-timing.https.html [ Pass Failure ]
 crbug.com/799137 [ Mac ] virtual/modern-media-controls/media/controls/modern/doubletap-to-jump-backwards-at-start.html [ Pass Timeout ]
 
+# This test is flaking (failing, crashing) on mac_chromium_rel_ng.
+crbug.com/800840 [ Mac ] virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html [ Skip ]
+
 # Sheriff failures 2018-01-23
 # Flaking on linux_chromium_rel_ng
 crbug.com/804709 [ Linux ] virtual/gpu/fast/canvas/canvas-fillPath-shadow.html [ Pass Failure ]

third_party/WebKit/LayoutTests/VirtualTestSuites

@@ -319,13 +319,7 @@
   },
   {
     "prefix": "wheelscrolllatching",
-    "base": "fast/compositor-wheel-scroll-latching/animated-scroll",
-    "args": ["--enable-features=TouchpadAndWheelScrollLatching",
-             "--enable-threaded-compositing"]
-  },
-  {
-    "prefix": "wheelscrolllatching",
-    "base": "fast/compositor-wheel-scroll-latching/non-animated-scroll",
+    "base": "fast/compositor-wheel-scroll-latching",
     "args": ["--enable-features=TouchpadAndWheelScrollLatching",
              "--enable-threaded-compositing",
              "--disable-smooth-scrolling"]

third_party/WebKit/LayoutTests/fast/compositor-wheel-scroll-latching/non-animated-scroll/subpixel-accumulation.html → third_party/WebKit/LayoutTests/fast/compositor-wheel-scroll-latching/subpixel-accumulation.html

 <!DOCTYPE html>
-<script src="../../../resources/testharness.js"></script>
-<script src="../../../resources/testharnessreport.js"></script>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
 <script>
   let t;
   if (window.internals && chrome && chrome.gpuBenchmarking) {

third_party/WebKit/LayoutTests/fast/compositor-wheel-scroll-latching/animated-scroll/touchpad-scroll-impl-to-main.html → third_party/WebKit/LayoutTests/fast/compositor-wheel-scroll-latching/touchpad-scroll-impl-to-main.html

 <!DOCTYPE HTML>
-<script src="../../../resources/testharness.js"></script>
-<script src="../../../resources/testharnessreport.js"></script>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
 <style>
   body {
     margin: 0px;
@@ -29,21 +29,21 @@ var rect = div.getBoundingClientRect();
 const GESTURE_SOURCE_TYPE = 2; // MOUSE_INPUT from synthetic_gesture_params.h
 
 function changeStyleToScrollOnMain() {
-  if(div.scrollTop > 100)
+  if(div.scrollTop > 150)
     div.style = "border-radius:40px; position:fixed;";
 }
-div.addEventListener("wheel", changeStyleToScrollOnMain, {passive: true});
+div.addEventListener("scroll", changeStyleToScrollOnMain, {passive: true});
 
+const MAX_RAF = 1000;
 let last_scroll_offset = div.scrollTop;
 var last_changed_count = 0;
 var raf_count = 0;
 function waitForAnimationEnd() {
   return new Promise((resolve, reject) => {
     function tick() {
-    // We requestAnimationFrame until either 70 frames with no change observed
-    // or the div is fully scrolled.
-      if (raf_count - last_changed_count > 70 ||
-          div.scrollTop == div.scrollHeight - div.clientHeight) {
+    // We requestAnimationFrame either for 1000 frames or until 20 frames with
+    // no change have been observed.
+      if (raf_count >= MAX_RAF || raf_count - last_changed_count > 20) {
         resolve();
       } else {
         if (div.scrollTop != last_scroll_offset) {
@@ -66,7 +66,7 @@ promise_test(() => {
                                           (rect.top + rect.bottom) / 2,
                                           GESTURE_SOURCE_TYPE,
                                           'down',
-                                          2000);
+                                          4000);
   }).then(waitForAnimationEnd)
   .then(() => {
     assert_equals(div.scrollTop, div.scrollHeight - div.clientHeight,

third_party/WebKit/LayoutTests/virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/non-animated-scroll/README.txt → third_party/WebKit/LayoutTests/virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/README.txt

-This suite runs the tests in fast/compositor-wheel-scroll-latching/non-animated-scroll with
+This suite runs the tests in fast/compositor-wheel-scroll-latching with
 # --enable-features=TouchpadAndWheelScrollLatching  --enable-threaded-compositing --disable-smooth-scrolling

third_party/WebKit/LayoutTests/virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latching/animated-scroll/README.txt

-This suite runs the tests in fast/compositor-wheel-scroll-latching/animated-scroll with
-# --enable-features=TouchpadAndWheelScrollLatching  --enable-threaded-compositing

ui/events/blink/input_handler_proxy.cc

@@ -765,12 +765,7 @@ InputHandlerProxy::HandleGestureScrollUpdate(
         return DID_HANDLE;
       case cc::InputHandler::SCROLL_IGNORED:
         return DROP_EVENT;
-      case cc::InputHandler::SCROLL_ON_MAIN_THREAD:
-      case cc::InputHandler::SCROLL_UNKNOWN:
-        if (input_handler_->ScrollingShouldSwitchtoMainThread()) {
-          gesture_scroll_on_impl_thread_ = false;
-          client_->GenerateScrollBeginAndSendToMainThread(gesture_event);
-        }
+      default:
         return DID_NOT_HANDLE;
     }
   }