Reland: Respect the smooth scrolling setting in LayerScrollableArea.

This relands https://blink.lc/blink/commit/?id=5668429, which was reverted in
https://blink.lc/blink/commit/?id=a1303a8.

The Mac trackpad regression is addressed by
https://blink.lc/blink/commit/?id=021397d.

BUG=575,417782

Review URL: https://codereview.chromium.org/882813005

git-svn-id: svn://svn.chromium.org/blink/trunk@190675 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/TestExpectations

@@ -1729,6 +1729,9 @@ crbug.com/441738 inspector/extensions/extensions-network.html [ Pass Failure ]
 
 crbug.com/410949 http/tests/security/local-image-from-remote-whitelisted.html [ Pass Failure ]
 
+crbug.com/364614 [ Mac ] fast/scroll-behavior/overflow-scroll-animates.html [ Skip ]
+crbug.com/364614 [ Mac ] virtual/threaded/fast/scroll-behavior/overflow-scroll-animates.html [ Skip ]
+
 crbug.com/439856 virtual/deferred/fast/images/pixelated-composited.html [ ImageOnlyFailure ]
 crbug.com/442181 virtual/slimmingpaint/fast/images/pixelated-composited.html [ ImageOnlyFailure ]
 

third_party/WebKit/LayoutTests/fast/scroll-behavior/precise-delta-no-animate-expected.txt → third_party/WebKit/LayoutTests/fast/scroll-behavior/overflow-scroll-animates-expected.txt

-Tests that a WebMouseWheelEvent with hasPreciseScrollingDeltas does not produce an animated scroll
+Tests that overflow scrolls are animated, unless the wheel event has precise scrolling deltas.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
+PASS element.scrollTop is not 80
+PASS scrollDuration < 500 is true
 PASS element.scrollTop is 80
 PASS successfullyParsed is true
 

third_party/WebKit/LayoutTests/fast/scroll-behavior/precise-delta-no-animate.html → third_party/WebKit/LayoutTests/fast/scroll-behavior/overflow-scroll-animates.html

@@ -24,19 +24,58 @@
 jsTestIsAsync = true;
 element = document.getElementById("container");
 
-function runTest() {
-    element.addEventListener("scroll", function() {
-        shouldBe("element.scrollTop", "80");
+var testConfigs = [
+  {preciseDeltas: false, expectSmooth: true},
+  {preciseDeltas: true, expectSmooth: false},
+];
+var config;
+var waitingForScroll = false;
+var scrollStart, scrollDuration;
+
+function nextConfig() {
+    config = testConfigs.shift();
+    if (!config)
         finishJSTest();
-    });
+
+    element.addEventListener("scroll", onElementScroll);
 
     eventSender.mouseMoveTo(100, 100);
     eventSender.mouseScrollBy(0, -2, /* paged */ false,
-        /* has_precise_scrolling_deltas */ true);
+        config.preciseDeltas);
+    scrollStart = performance.now();
+}
+
+function reset() {
+    element.removeEventListener("scroll", onElementScroll);
+    element.scrollTop = 0;
+    waitingForScroll = false;
+}
+
+function onElementScroll() {
+    if (waitingForScroll) {
+        if (element.scrollTop == 80) {
+            scrollDuration = performance.now() - scrollStart;
+            shouldBeTrue("scrollDuration < 500");
+            reset();
+            nextConfig();
+        }
+    } else if (config.expectSmooth) {
+        shouldNotBe("element.scrollTop", "80");
+        waitingForScroll = true;
+    } else {
+        shouldBe("element.scrollTop", "80");
+        reset();
+        nextConfig();
+    }
+}
+
+function runTest() {
+    internals.settings.setScrollAnimatorEnabled(true);
+    nextConfig();
 }
 
-description("Tests that a WebMouseWheelEvent with hasPreciseScrollingDeltas " +
-            "does not produce an animated scroll");
+description("Tests that overflow scrolls are animated, unless the wheel " +
+            "event has precise scrolling deltas.");
 
 if (window.eventSender)
     runTest();

third_party/WebKit/Source/core/layout/LayerScrollableArea.cpp

@@ -488,6 +488,13 @@ IntPoint LayerScrollableArea::lastKnownMousePosition() const
     return box().frame() ? box().frame()->eventHandler().lastKnownMousePosition() : IntPoint();
 }
 
+bool LayerScrollableArea::scrollAnimatorEnabled() const
+{
+    if (Settings* settings = box().frame()->settings())
+        return settings->scrollAnimatorEnabled();
+    return false;
+}
+
 bool LayerScrollableArea::shouldSuspendScrollAnimations() const
 {
     RenderView* view = box().view();

third_party/WebKit/Source/core/layout/LayerScrollableArea.h

@@ -107,6 +107,7 @@ public:
     virtual IntSize contentsSize() const override;
     virtual IntSize overhangAmount() const override;
     virtual IntPoint lastKnownMousePosition() const override;
+    virtual bool scrollAnimatorEnabled() const override;
     virtual bool shouldSuspendScrollAnimations() const override;
     virtual bool scrollbarsCanBeActive() const override;
     virtual IntRect scrollableAreaBoundingBox() const override;

third_party/WebKit/Source/web/WebPagePopupImpl.cpp

@@ -243,6 +243,7 @@ bool WebPagePopupImpl::initializePage()
     m_page->settings().setDeviceSupportsTouch(m_webView->page()->settings().deviceSupportsTouch());
     // FIXME: Should we support enabling a11y while a popup is shown?
     m_page->settings().setAccessibilityEnabled(m_webView->page()->settings().accessibilityEnabled());
+    m_page->settings().setScrollAnimatorEnabled(m_webView->page()->settings().scrollAnimatorEnabled());
 
     provideContextFeaturesTo(*m_page, adoptPtr(new PagePopupFeaturesClient()));
     static FrameLoaderClient* emptyFrameLoaderClient = new EmptyFrameLoaderClient();