Revert "[Reland#2] Make programmatic scrolls respect smooth scroll flag"

This reverts commit b746c948.

Reason for revert: Still failing on Mac web tests: https://ci.chromium.org/p/chromium/builders/ci/Mac10.13%20Tests%20%28dbg%29/16983

Original change's description:
> [Reland#2] Make programmatic scrolls respect smooth scroll flag
> 
> Programmatic smooth scrolls should also be instant if the smooth scroll
> flag is explicitly disabled.
> 
> Previously landed in https://crrev.com/c/1536759 and in
> https://crrev.com/c/2009842
> 
> To reland, this CL force enables the scroll animator in Blink web
> tests. Without this, the usual flow for determining if the animator is
> enabled is followed, which leads to inconsistencies. On Mac, the
> animator is enabled in Chrome but not in content shell. This leads to
> inconsistencies with other platforms (Mac tests ran without smooth
> scroll while Linux/Windows ran with) and ensuring we test what we ship.
> 
> This change required some minor fixes to tests that assumed instant
> scroll on Mac (and uncovered one real bug).
> 
> Second reland fixes a few more tests on Mac. See diff from original
> patchset for changes.
> 
> TBR=flackr@chromium.org,nasko@chromium.org
> 
> Bug: 944583
> Change-Id: Ib91c417f1fcc2b27601f2c7039b02da72b9d5420
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2022356
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#735480}

TBR=flackr@chromium.org,nasko@chromium.org,bokan@chromium.org

Change-Id: Ifad1c0b6a19f222391c2361e80c699d27da7576b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 944583
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2024412Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735704}

content/shell/renderer/web_test/blink_test_helpers.cc

@@ -117,8 +117,6 @@ void ApplyWebTestDefaultPreferences(WebPreferences* prefs) {
   prefs->strict_mixed_content_checking = false;
   prefs->strict_powerful_feature_restrictions = false;
   prefs->webgl_errors_to_console_enabled = false;
-  prefs->enable_scroll_animator =
-      !command_line.HasSwitch(switches::kDisableSmoothScrolling);
   base::string16 serif;
 #if defined(OS_MACOSX)
   prefs->cursive_font_family_map[kCommonScript] =

third_party/blink/renderer/core/frame/root_frame_viewport_test.cc

@@ -83,7 +83,6 @@ class ScrollableAreaStub : public GarbageCollected<ScrollableAreaStub>,
     DEFINE_STATIC_LOCAL(ScrollbarThemeOverlayMock, theme, ());
     return theme;
   }
-  bool ScrollAnimatorEnabled() const override { return true; }
 
   void Trace(blink::Visitor* visitor) override {
     ScrollableArea::Trace(visitor);
@@ -215,7 +214,7 @@ TEST_F(RootFrameViewportTest, UserInputScrollable) {
 
   // Layout viewport shouldn't scroll since it's not horizontally scrollable,
   // but visual viewport should.
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(300, 0),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(0, 0), layout_viewport->GetScrollOffset());
@@ -223,7 +222,7 @@ TEST_F(RootFrameViewportTest, UserInputScrollable) {
   EXPECT_EQ(ScrollOffset(50, 0), root_frame_viewport->GetScrollOffset());
 
   // Vertical scrolling should be unaffected.
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(0, 300),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(0, 150), layout_viewport->GetScrollOffset());
@@ -247,7 +246,7 @@ TEST_F(RootFrameViewportTest, UserInputScrollable) {
 
   // Layout viewport shouldn't scroll since it's not vertically scrollable,
   // but visual viewport should.
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(0, 300),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(0, 0), layout_viewport->GetScrollOffset());
@@ -255,7 +254,7 @@ TEST_F(RootFrameViewportTest, UserInputScrollable) {
   EXPECT_EQ(ScrollOffset(0, 75), root_frame_viewport->GetScrollOffset());
 
   // Horizontal scrolling should be unaffected.
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(300, 0),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(100, 0), layout_viewport->GetScrollOffset());
@@ -293,7 +292,7 @@ TEST_F(RootFrameViewportTest, TestScrollAnimatorUpdatedBeforeScroll) {
   visual_viewport->SetScrollOffset(ScrollOffset(50, 75), kProgrammaticScroll);
   EXPECT_EQ(ScrollOffset(50, 75), root_frame_viewport->GetScrollOffset());
 
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(-50, 0),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(0, 75), root_frame_viewport->GetScrollOffset());
@@ -306,7 +305,7 @@ TEST_F(RootFrameViewportTest, TestScrollAnimatorUpdatedBeforeScroll) {
   layout_viewport->SetScrollOffset(ScrollOffset(100, 150), kProgrammaticScroll);
   EXPECT_EQ(ScrollOffset(100, 150), root_frame_viewport->GetScrollOffset());
 
-  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPrecisePixel,
+  root_frame_viewport->UserScroll(ScrollGranularity::kScrollByPixel,
                                   FloatSize(-100, 0),
                                   ScrollableArea::ScrollCallback());
   EXPECT_EQ(ScrollOffset(0, 150), root_frame_viewport->GetScrollOffset());

third_party/blink/renderer/core/scroll/scrollable_area.cc

@@ -315,7 +315,7 @@ void ScrollableArea::ProgrammaticScrollHelper(const ScrollOffset& offset,
         std::move(callback), WrapWeakPersistent(this)));
   }
 
-  if (scroll_behavior == kScrollBehaviorSmooth && ScrollAnimatorEnabled()) {
+  if (scroll_behavior == kScrollBehaviorSmooth) {
     GetProgrammaticScrollAnimator().AnimateToOffset(offset, is_sequenced_scroll,
                                                     std::move(callback));
   } else {

third_party/blink/renderer/core/scroll/scrollable_area_test.cc

@@ -24,26 +24,8 @@ namespace blink {
 namespace {
 
 using testing::_;
-using testing::Mock;
 using testing::Return;
 
-class MockAnimatingScrollableArea : public MockScrollableArea {
- public:
-  static MockAnimatingScrollableArea* Create() {
-    return MakeGarbageCollected<MockAnimatingScrollableArea>();
-  }
-  static MockAnimatingScrollableArea* Create(
-      const ScrollOffset& maximum_scroll_offset) {
-    MockAnimatingScrollableArea* mock = Create();
-    mock->SetMaximumScrollOffset(maximum_scroll_offset);
-    return mock;
-  }
-  Scrollbar* HorizontalScrollbar() const override { return nullptr; }
-  Scrollbar* VerticalScrollbar() const override { return nullptr; }
-  MOCK_CONST_METHOD0(ScrollAnimatorEnabled, bool());
-  MOCK_METHOD0(ScheduleAnimation, bool());
-};
-
 class ScrollbarThemeWithMockInvalidation : public ScrollbarThemeOverlayMock {
  public:
   MOCK_CONST_METHOD0(ShouldRepaintAllPartsOnInvalidation, bool());
@@ -288,35 +270,6 @@ TEST_F(ScrollableAreaTest, ScrollableAreaDidScroll) {
   EXPECT_EQ(51, scrollable_area->ScrollOffsetInt().Height());
 }
 
-TEST_F(ScrollableAreaTest, ProgrammaticScrollRespectAnimatorEnabled) {
-  ScopedTestingPlatformSupport<TestingPlatformSupportWithMockScheduler>
-      platform;
-  MockAnimatingScrollableArea* scrollable_area =
-      MockAnimatingScrollableArea::Create(ScrollOffset(0, 100));
-  // Disable animations. Make sure an explicitly smooth programmatic scroll is
-  // instantly scrolled.
-  {
-    EXPECT_CALL(*scrollable_area, ScrollAnimatorEnabled())
-        .WillRepeatedly(Return(false));
-    EXPECT_CALL(*scrollable_area, ScheduleAnimation()).Times(0);
-    scrollable_area->SetScrollOffset(ScrollOffset(0, 100), kProgrammaticScroll,
-                                     kScrollBehaviorSmooth);
-    EXPECT_EQ(100, scrollable_area->GetScrollOffset().Height());
-  }
-  Mock::VerifyAndClearExpectations(scrollable_area);
-  // Enable animations. A smooth programmatic scroll should now schedule an
-  // animation rather than immediately mutating the offset.
-  {
-    EXPECT_CALL(*scrollable_area, ScrollAnimatorEnabled())
-        .WillRepeatedly(Return(true));
-    EXPECT_CALL(*scrollable_area, ScheduleAnimation()).WillOnce(Return(true));
-    scrollable_area->SetScrollOffset(ScrollOffset(0, 50), kProgrammaticScroll,
-                                     kScrollBehaviorSmooth);
-    // Offset is unchanged.
-    EXPECT_EQ(100, scrollable_area->GetScrollOffset().Height());
-  }
-}
-
 // Scrollbars in popups shouldn't fade out since they aren't composited and thus
 // they don't appear on hover so users without a wheel can't scroll if they fade
 // out.

third_party/blink/renderer/core/scroll/scrollbar_test_suite.h

@@ -93,7 +93,7 @@ class MockScrollableArea : public GarbageCollected<MockScrollableArea>,
   CompositorElementId GetScrollElementId() const override {
     return CompositorElementId();
   }
-  bool ScrollAnimatorEnabled() const override { return true; }
+  bool ScrollAnimatorEnabled() const override { return false; }
   int PageStep(ScrollbarOrientation) const override { return 0; }
   void ScrollControlWasSetNeedsPaintInvalidation() override {}
   IntPoint ConvertFromRootFrame(const IntPoint& point_in_root_frame) const {
@@ -129,12 +129,11 @@ class MockScrollableArea : public GarbageCollected<MockScrollableArea>,
     ScrollableArea::Trace(visitor);
   }
 
- protected:
+ private:
   void SetMaximumScrollOffset(const ScrollOffset& maximum_scroll_offset) {
     maximum_scroll_offset_ = maximum_scroll_offset;
   }
 
- private:
   ScrollOffset scroll_offset_;
   ScrollOffset maximum_scroll_offset_;
   Member<MockPlatformChromeClient> chrome_client_;

third_party/blink/web_tests/TestExpectations

@@ -5189,11 +5189,6 @@ crbug.com/875884 [ Linux ] lifecycle/background-change-lifecycle-count.html [ Pa
 crbug.com/875884 [ Win ] lifecycle/background-change-lifecycle-count.html [ Pass Failure ]
 crbug.com/875884 [ Win ] virtual/threaded/lifecycle/background-change-lifecycle-count.html [ Pass Failure ]
 
-# Broken when smooth scrolling was enabled in Mac web tests (real failure)
-crbug.com/1044137 [ Mac ] fast/scrolling/no-hover-during-smooth-keyboard-scroll.html [ Failure ]
-crbug.com/1044137 [ Mac ] virtual/scroll_customization/fast/scrolling/no-hover-during-smooth-keyboard-scroll.html [ Failure ]
-crbug.com/1044137 [ Mac ] virtual/threaded-prefer-compositing/fast/scrolling/no-hover-during-smooth-keyboard-scroll.html [ Failure ]
-
 # Test frequently times out on Mac CQ bots.
 crbug.com/874703 [ Mac ] http/tests/devtools/extensions/extensions-panel.js [ Timeout Pass ]
 

third_party/blink/web_tests/fast/dom/vertical-scrollbar-in-rtl-expected.txt

@@ -4,8 +4,8 @@ vertical scroll: : Success
 continuously call window.scrollY : Success
 zoom in and out preserve scroll position: Success
 resize preserves scroll position: Success
-Home key scrolls to top: Success
-End key scrolls to bottom: Success
+PASS window.scrollY == -3425 became true
+PASS window.scrollY == 0 became true
 selectAll selects all document: Success
 PASS successfullyParsed is true
 

third_party/blink/web_tests/fast/dom/vertical-scrollbar-in-rtl.html

 <html dir=rtl style="-webkit-writing-mode:vertical-lr">
     <head>
         <script src="../../resources/js-test.js"></script>
-        <script src="../../resources/gesture-util.js"></script>
         <script language="javascript">
             window.jsTestIsAsync = true;
 
@@ -33,7 +32,7 @@
             var expectedScrollX = 500;
             var expectedScrollY = -1000;
 
-            onload = async function()
+            onload = function()
             {
                 if (window.testRunner)
                     testRunner.dumpAsText();
@@ -64,34 +63,20 @@
 
                 // Test HOME/END operation.
                 if (window.eventSender) {
-                    // Note: in Mac, HOME/END key resets the scroll position in
-                    // the x direction first, then y on a second call. This
-                    // differs from other platforms where HOME/END key only
-                    // reset y scroll position, and x scroll position is
-                    // preserved.
-                    async function testEnd() {
+                    // Not using assert equal here since the behavior is different in each port.
+                    // For example, in Mac, HOME/END key reset both x and y scroll position.
+                    // In Chromium, HOME/END key only reset y scroll position, and x scroll position is preserved.
+                    function testEnd() {
                         window.scrollTo(expectedScrollX, expectedScrollY);
                         eventSender.keyDown("End");
-                        await waitForCompositorCommit();
-                        await waitForAnimationEndTimeBased(() => { return window.scrollX; });
-                        eventSender.keyDown("End");
-                        await waitForCompositorCommit();
-                        await waitForAnimationEndTimeBased(() => { return window.scrollY; });
-                        assertEqual("End key scrolls to bottom", window.scrollY, 0);
+                        shouldBecomeEqual('window.scrollY == 0', 'true', testSelectAll);
                     }
-                    async function testHome() {
+                    function testHome() {
                         window.scrollTo(expectedScrollX, expectedScrollY);
                         eventSender.keyDown("Home");
-                        await waitForCompositorCommit();
-                        await waitForAnimationEndTimeBased(() => { return window.scrollX; });
-                        eventSender.keyDown("Home");
-                        await waitForCompositorCommit();
-                        await waitForAnimationEndTimeBased(() => { return window.scrollY; });
-                        assertEqual("Home key scrolls to top", window.scrollY, -3425);
+                        shouldBecomeEqual('window.scrollY == -3425', 'true', testEnd);
                     }
-                    await testHome();
-                    await waitForCompositorCommit();
-                    await testEnd();
+                    testHome();
                 }
 
                 function testSelectAll() {
@@ -105,8 +90,6 @@
 
                     finishJSTest();
                 }
-
-                testSelectAll();
             }
         </script>
     </head>

third_party/blink/web_tests/fast/events/keyboard-scroll-by-page.html

@@ -2,7 +2,6 @@
 <html>
 <head>
 <script src="../../resources/js-test.js"></script>
-<script src="../../resources/gesture-util.js"></script>
 <style type="text/css">
 ::-webkit-scrollbar {
     width: 0px;
@@ -31,7 +30,7 @@
 <div id="console"></div>
 <script type="text/javascript">
 
-async function keyboardScrollPageDown()
+function keyboardScrollPageDown()
 {
     if (navigator.platform.indexOf('Mac') == 0) {
         eventSender.keyDown('ArrowDown', ["altKey"]);
@@ -39,14 +38,11 @@ async function keyboardScrollPageDown()
         eventSender.keyDown('PageDown');
     }
 
-    await waitForCompositorCommit();
-    await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
-
     // see kMinFractionToStepWhenPaging = 0.875f in ScrollableArea.cpp
     shouldBecomeEqual("document.scrollingElement.scrollTop >= window.innerHeight * 0.875", "true", keyboardScrollPageUp);
 }
 
-async function keyboardScrollPageUp()
+function keyboardScrollPageUp()
 {
     if (navigator.platform.indexOf('Mac') == 0) {
         eventSender.keyDown('ArrowUp', ["altKey"]);
@@ -54,16 +50,13 @@ async function keyboardScrollPageUp()
         eventSender.keyDown('PageUp');
     }
 
-    await waitForCompositorCommit();
-    await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
-
     // PageDown + PageUp goes back to 0
     shouldBecomeEqual("document.scrollingElement.scrollTop", "0", finishJSTest);
 }
 
 jsTestIsAsync = true;
 
-async function runTest()
+function runTest()
 {
     if (window.eventSender) {
         description('This tests keyboard scrolling by pages.');

third_party/blink/web_tests/fast/events/platform-wheelevent-paging-xy-in-scrolling-page.html

 <html>
     <head>
         <script src="../../resources/js-test.js"></script>
-        <script src="../../resources/gesture-util.js"></script>
         <script>
             window.jsTestIsAsync = true;
             var isMacOSX = navigator.userAgent.indexOf("Mac OS X") >= 0;
@@ -24,16 +23,13 @@
             var event;
             var div;
 
-            async function runTest()
+            function runTest()
             {
                 document.body.addEventListener("mousewheel", mousewheelHandler, false);
 
                 if (window.eventSender) {
                     eventSender.mouseMoveTo(100, 110);
                     eventSender.continuousMouseScrollBy(-window.givenScrollLeft, -window.givenScrollTop, true);
-                    await waitForCompositorCommit();
-                    await waitForAnimationEndTimeBased(() => {return document.scrollingElement.scrollTop;});
-                    await waitForAnimationEndTimeBased(() => {return document.scrollingElement.scrollLeft;});
                 }
 
                 shouldBecomeEqual("document.scrollingElement.scrollTop == window.expectedScrollTop && " +

third_party/blink/web_tests/fast/events/space-scroll-textinput-canceled.html

@@ -2,7 +2,6 @@
 <html>
 <head>
 <script src="../../resources/js-test.js"></script>
-<script src="../../resources/gesture-util.js"></script>
 <style type="text/css">
 ::-webkit-scrollbar {
     width: 0px;
@@ -28,7 +27,7 @@ txt.addEventListener('textInput', function(e) {
     }
 }, false);
 
-async function focusAndPressSpace()
+function focusAndPressSpace()
 {
     document.getElementById('txt').focus();
     // Leave some space for PageUp
@@ -38,16 +37,13 @@ async function focusAndPressSpace()
     // Space key shouldn't cancel PageUp
     eventSender.keyDown(" ", []);
 
-    await waitForCompositorCommit();
-    await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
-
     // PageUp should finish
     shouldBecomeEqual("document.scrollingElement.scrollTop", "0", finishJSTest);
 }
 
 jsTestIsAsync = true;
 
-async function runTest()
+function runTest()
 {
     if (window.eventSender) {
         focusAndPressSpace();

third_party/blink/web_tests/fast/scrolling/no-hover-during-smooth-keyboard-scroll.html

@@ -59,27 +59,21 @@
       assert_false(array[1].matches(":hover"));
       assert_equals(document.scrollingElement.scrollTop, 0);
 
-      // Keyboard scroll end up at 4th element. Hover state does not update
-      // during scrolling, only the 4th element has a hover effect. We wait for
-      // the end of each scroll animation for consistency; Mac differs from
-      // other platforms in how ongoing scroll animations are updated.
+      // Keyboard scroll end up at 4th element. Hover state does not update during scrolling,
+      // only the 4th element has a hover effect.
       eventSender.keyDown('ArrowDown');
-      await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
       eventSender.keyDown('ArrowDown');
-      await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
       eventSender.keyDown('ArrowDown');
-      await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
       eventSender.keyDown('ArrowDown');
-      await waitForAnimationEndTimeBased(() => { return document.scrollingElement.scrollTop; });
-
-      // Make sure we update the  hover state when the scroll animation is finished.
+      // Wait enough time to see if we fire a fake mouse move event to update the hover state.
+      await waitForAnimationEnd(() => { return document.scrollingElement.scrollTop; }, 300, 15);
       assert_approx_equals(document.scrollingElement.scrollTop, 3 * elementHeight, 25);
-      assert_false(array[0].matches(":hover"), "first element unexpectedly hovered");
-      assert_false(array[1].matches(":hover"), "second element unexpectedly hovered");
-      assert_false(array[2].matches(":hover"), "third element unexpectedly hovered");
-      assert_true(array[3].matches(":hover"), "expected element not hovered");
-      assert_false(array[4].matches(":hover"), "fifth element unexpectedly hovered");
+      assert_false(array[0].matches(":hover"));
+      assert_false(array[1].matches(":hover"));
+      assert_false(array[2].matches(":hover"));
+      assert_true(array[3].matches(":hover"));
+      assert_false(array[4].matches(":hover"));
     }, 'Keyboard smooth scroll on the page, no hover update during scrolling, but updating hover at the end of scroll.');
   }
 
-</script>
+</script>
\ No newline at end of file

third_party/blink/web_tests/fast/spatial-navigation/snav-unit-overflow-and-scroll-in-direction.html

@@ -43,6 +43,7 @@
       testRunner.dumpAsText();
       testRunner.overridePreference("WebKitTabToLinksPreferenceKey", 1);
       testRunner.overridePreference("WebKitSpatialNavigationEnabled", 1);
+      internals.settings.setScrollAnimatorEnabled(false);
       testRunner.waitUntilDone();
     }
 
@@ -67,10 +68,8 @@
       shouldBeTrue(String(document.scrollingElement.scrollTop != 0));
 
       // Then it scrolls down to the end of the page ...
-      if (window.eventSender) {
-        internals.settings.setScrollAnimatorEnabled(false);
+      if (window.eventSender)
         eventSender.keyDown("End");
-      }
 
       // And 'resultMap2' re-tries to move focus down.
       initTest(resultMap2, step2Completed);

third_party/blink/web_tests/platform/mac/fast/events/scrollbar-double-click-expected.txt

-Scroll offset is 360
+Scroll offset is 720

third_party/blink/web_tests/resources/gesture-util.js

@@ -89,45 +89,6 @@ function waitForAnimationEnd(getValue, max_frame, max_unchanged_frame) {
   })
 }
 
-// TODO(bokan): Replace uses of the above with this one.
-function waitForAnimationEndTimeBased(getValue) {
-  // Give up if the animation still isn't done after this many milliseconds.
-  const TIMEOUT_MS = 1000;
-
-  // If the value is unchanged for this many milliseconds, we consider the
-  // animation ended and return.
-  const END_THRESHOLD_MS = 200;
-
-  const START_TIME = performance.now();
-
-  let last_changed_time = START_TIME;
-  let last_value = getValue();
-  return new Promise((resolve, reject) => {
-    function tick() {
-      let cur_time = performance.now();
-
-      if (cur_time - last_changed_time > END_THRESHOLD_MS) {
-        resolve();
-        return;
-      }
-
-      if (cur_time - START_TIME > TIMEOUT_MS) {
-        reject();
-        return;
-      }
-
-      let current_value = getValue();
-      if (last_value != current_value) {
-        last_changed_time = cur_time;
-        last_value = current_value;
-      }
-
-      requestAnimationFrame(tick);
-    }
-    tick();
-  })
-}
-
 // Enums for gesture_source_type parameters in gpuBenchmarking synthetic
 // gesture methods. Must match C++ side enums in synthetic_gesture_params.h
 const GestureSourceType = (function() {