Move logic of recording main thread scrolling reasons from cc to blink::ScrollManager

third_party/WebKit/Source/core/input/EventHandlerTest.cpp

Index: third_party/WebKit/Source/core/input/EventHandlerTest.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandlerTest.cpp b/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
index f8618151f6be13253f4f4efeefa617b8fe13d3b2..aa40b9d50699a6d6daedb6ad30cfae2e7b76a9f2 100644
--- a/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
@@ -16,6 +16,7 @@
 #include "core/page/AutoscrollController.h"
 #include "core/page/Page.h"
 #include "core/testing/DummyPageHolder.h"
+#include "platform/testing/HistogramTester.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
@@ -79,6 +80,29 @@ class MousePressEventBuilder : public WebMouseEvent {
   }
 };
 
+class ScrollBeginEventBuilder : public WebGestureEvent {
+ public:
+  ScrollBeginEventBuilder(IntPoint position,
+                          FloatPoint delta,
+                          WebGestureDevice device)
+      : WebGestureEvent() {
+    m_type = WebInputEvent::GestureScrollBegin;
+    x = globalX = position.x();
+    y = globalY = position.y();
+    data.scrollBegin.deltaYHint = delta.y();
+    sourceDevice = device;
+    m_frameScale = 1;
+  }
+};
+
+class ScrollEndEventBuilder : public WebGestureEvent {
+ public:
+  ScrollEndEventBuilder() : WebGestureEvent() {
+    m_type = WebInputEvent::GestureScrollEnd;
+    m_frameScale = 1;
+  }
+};
+
 void EventHandlerTest::SetUp() {
   m_dummyPageHolder = DummyPageHolder::create(IntSize(300, 400));
 }
@@ -461,6 +485,78 @@ TEST_F(EventHandlerTest, dragEndInNewDrag) {
   // This test passes if it doesn't crash.
 }
 
+TEST_F(EventHandlerTest, NonCompositedMainThreadScrollingReasonTest) {
+  setHtmlInnerHTML(
+      "<style>.box { width: 100px; height: 100px; overflow: scroll; }"
+      " .translucent { opacity: 0.5;}"
+      " .spacer { height: 1000px;} body {height: 1000px; }"
+      " .background_scroller { overflow: scroll; width: 250px; height: 250px;"
+      "   position: absolute; z-index: -1;}"
+      " body { height: 2000px; width: 1000px;} "
+      "</style>"
+      "<div class='translucent box'><div class='spacer'></div></div>"
+      "<div id='under' class='background_scroller'><div "
+      "class='spacer'></div></div>"
+      "<div class='box' style='will-change:transform'><div "
+      "class='spacer'></div></div>");
+
+  page().settings().setAcceleratedCompositingEnabled(true);
+  document().view()->setParentVisible(true);
+  document().view()->setSelfVisible(true);
+  document().view()->updateAllLifecyclePhases();
+
+  HistogramTester histogramTester;
+  // Test wheel scroll.
+  ScrollBeginEventBuilder wheelScrollBegin(
+      IntPoint(50, 50), FloatPoint(0.f, 1.f), WebGestureDeviceTouchpad);
+  ScrollEndEventBuilder wheelScrollEnd;
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollEnd);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 17,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 19,
+                                    1);
+  histogramTester.expectTotalCount("Renderer4.MainThreadWheelScrollReason", 2);
+
+  // Composited scrolling doesn't add to the counts.
+  wheelScrollBegin.x = wheelScrollBegin.globalX = 450;
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollEnd);
+  histogramTester.expectTotalCount("Renderer4.MainThreadWheelScrollReason", 2);
+
+  // Scroll a composited scroller A over a non-composited scroller B should
+  // cause the scroll events to go to the main thread because B is non fast
+  // scrollable region. If none of the scrollers from A's containing scroll
+  // chain has a reason, UnknownNonCompositedRegion should be added.
+  wheelScrollBegin.x = wheelScrollBegin.globalX = 50;
+  wheelScrollBegin.y = wheelScrollBegin.globalY = 150;
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollEnd);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 23,
+                                    1);
+
+  // UnknownNonCompositedRegion is not added if the scroller underneath has a
+  // reason.
+  document().getElementById("under")->setAttribute("style", "position:fixed;");
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(wheelScrollEnd);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 23,
+                                    1);
+  // Test touch scroll.
+  ScrollBeginEventBuilder touchScrollBegin(
+      IntPoint(50, 50), FloatPoint(0.f, 1.f), WebGestureDeviceTouchscreen);
+  ScrollEndEventBuilder touchScrollEnd;
+  document().frame()->eventHandler().handleGestureEvent(touchScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(touchScrollEnd);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    17, 1);
+
+  document().frame()->eventHandler().handleGestureEvent(touchScrollBegin);
+  document().frame()->eventHandler().handleGestureEvent(touchScrollEnd);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    17, 2);
+}
+
 class TooltipCapturingChromeClient : public EmptyChromeClient {
  public:
   TooltipCapturingChromeClient() {}