Record size of scroller that user scrolls

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 fd1d83710e613c6562a55c148db4514b11f6f1ee..2817b385648d5d982f9edf26d5fd9ce45aadfd5a 100644
--- a/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
@@ -20,6 +20,7 @@
 #include "core/paint/PaintLayerScrollableArea.h"
 #include "core/testing/DummyPageHolder.h"
 #include "platform/scroll/MainThreadScrollingReason.h"
+#include "platform/scroll/ScrollerSize.h"
 #include "platform/testing/HistogramTester.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -52,8 +53,8 @@ class EventHandlerTest : public ::testing::Test {
   FrameSelection& Selection() const {
     return GetDocument().GetFrame()->Selection();
   }
-
   void SetHtmlInnerHTML(const char* html_content);
+  void Scroll(Element*, const WebGestureDevice);
 
  protected:
   std::unique_ptr<DummyPageHolder> dummy_page_holder_;
@@ -62,43 +63,7 @@ class EventHandlerTest : public ::testing::Test {
 class NonCompositedMainThreadScrollingReasonRecordTest
     : public EventHandlerTest {
  protected:
-  class ScrollBeginEventBuilder : public WebGestureEvent {
-   public:
-    ScrollBeginEventBuilder(IntPoint position,
-                            FloatPoint delta,
-                            WebGestureDevice device)
-        : WebGestureEvent() {
-      type_ = WebInputEvent::kGestureScrollBegin;
-      x = global_x = position.X();
-      y = global_y = position.Y();
-      data.scroll_begin.delta_y_hint = delta.Y();
-      source_device = device;
-      frame_scale_ = 1;
-    }
-  };
-
-  class ScrollUpdateEventBuilder : public WebGestureEvent {
-   public:
-    ScrollUpdateEventBuilder() : WebGestureEvent() {
-      type_ = WebInputEvent::kGestureScrollUpdate;
-      data.scroll_update.delta_x = 0.0f;
-      data.scroll_update.delta_y = 1.0f;
-      data.scroll_update.velocity_x = 0;
-      data.scroll_update.velocity_y = 1;
-      frame_scale_ = 1;
-    }
-  };
-
-  class ScrollEndEventBuilder : public WebGestureEvent {
-   public:
-    ScrollEndEventBuilder() : WebGestureEvent() {
-      type_ = WebInputEvent::kGestureScrollEnd;
-      frame_scale_ = 1;
-    }
-  };
-
   int GetBucketIndex(uint32_t reason);
-  void Scroll(Element*, const WebGestureDevice);
 };
 
 class TapEventBuilder : public WebGestureEvent {
@@ -146,6 +111,41 @@ class MousePressEventBuilder : public WebMouseEvent {
   }
 };
 
+class ScrollBeginEventBuilder : public WebGestureEvent {
+ public:
+  ScrollBeginEventBuilder(IntPoint position,
+                          FloatPoint delta,
+                          WebGestureDevice device)
+      : WebGestureEvent() {
+    type_ = WebInputEvent::kGestureScrollBegin;
+    x = global_x = position.X();
+    y = global_y = position.Y();
+    data.scroll_begin.delta_y_hint = delta.Y();
+    source_device = device;
+    frame_scale_ = 1;
+  }
+};
+
+class ScrollUpdateEventBuilder : public WebGestureEvent {
+ public:
+  ScrollUpdateEventBuilder() : WebGestureEvent() {
+    type_ = WebInputEvent::kGestureScrollUpdate;
+    data.scroll_update.delta_x = 0.0f;
+    data.scroll_update.delta_y = 1.0f;
+    data.scroll_update.velocity_x = 0;
+    data.scroll_update.velocity_y = 1;
+    frame_scale_ = 1;
+  }
+};
+
+class ScrollEndEventBuilder : public WebGestureEvent {
+ public:
+  ScrollEndEventBuilder() : WebGestureEvent() {
+    type_ = WebInputEvent::kGestureScrollEnd;
+    frame_scale_ = 1;
+  }
+};
+
 void EventHandlerTest::SetUp() {
   dummy_page_holder_ = DummyPageHolder::Create(IntSize(300, 400));
 }
@@ -166,9 +166,7 @@ int NonCompositedMainThreadScrollingReasonRecordTest::GetBucketIndex(
   return index;
 }
 
-void NonCompositedMainThreadScrollingReasonRecordTest::Scroll(
-    Element* element,
-    const WebGestureDevice device) {
+void EventHandlerTest::Scroll(Element* element, const WebGestureDevice device) {
   DCHECK(element);
   DCHECK(element->getBoundingClientRect());
   ClientRect* rect = element->getBoundingClientRect();
@@ -581,6 +579,49 @@ TEST_F(EventHandlerTest, dragEndInNewDrag) {
   // This test passes if it doesn't crash.
 }
 
+TEST_F(EventHandlerTest,
+       ScrollerSizeOfMainThreadScrollingHistogramRecordingTest) {
+  SetHtmlInnerHTML(
+      "<style>"
+      " .container { width: 200px; height: 200px; overflow: scroll; }"
+      " .box { width: 100px; height: 100px; overflow: scroll; }"
+      " .spacer { height: 1000px;} body { height: 2000px; }"
+      "</style>"
+      "<div class='container'>"
+      " <div id='box' class='box'>"
+      "  <div id='content' class='spacer'></div>"
+      " </div>"
+      "</div>");
+
+  Element* box = GetDocument().getElementById("box");
+  HistogramTester histogram_tester;
+
+  // Test wheel scroll on the box.
+  Scroll(box, kWebGestureDeviceTouchpad);
+  histogram_tester.ExpectBucketCount("Event.Scroll.ScrollerSize.OnScroll_Wheel",
+                                     10000, 1);
+  // Only the first scrollable area is recorded.
+  histogram_tester.ExpectBucketCount("Event.Scroll.ScrollerSize.OnScroll_Wheel",
+                                     40000, 0);
+  histogram_tester.ExpectTotalCount("Event.Scroll.ScrollerSize.OnScroll_Wheel",
+                                    1);
+
+  // Test touch scroll on the main frame.

[bokan, 2017/04/18 19:24:39]

You're not trying to scroll the main frame here though, right?

[yigu, 2017/04/19 20:53:05]

No.

+  Scroll(box, kWebGestureDeviceTouchscreen);
+  histogram_tester.ExpectBucketCount("Event.Scroll.ScrollerSize.OnScroll_Touch",
+                                     10000, 1);
+  histogram_tester.ExpectTotalCount("Event.Scroll.ScrollerSize.OnScroll_Touch",
+                                    1);
+
+  // Scrolling root layer doesn't add to count.
+  Element* body = GetDocument().body();
+  Scroll(body, kWebGestureDeviceTouchscreen);

[bokan, 2017/04/18 19:24:39]

In general, this won't work since Scroll() will send an event to the middle of
the given box - it doesn't meant that box will be scrolled (e.g. .box or
.container might be at the middle coordinate). This may or may not work in this
case but you may want to add ASSERTS to check that the box that you're expecting
to scroll actually got scrolled. Both for your own assurance and the reader's

[yigu, 2017/04/19 20:53:05]

In general it may not work. But in the example above, scrolling in the center of
an element works. I added an ASSERT as you suggested in the function Scroll to
guarantee that.

+  histogram_tester.ExpectBucketCount("Event.Scroll.ScrollerSize.OnScroll_Touch",
+                                     kMaxScrollerSize, 0);
+  histogram_tester.ExpectTotalCount("Event.Scroll.ScrollerSize.OnScroll_Touch",
+                                    1);
+}
+
 class TooltipCapturingChromeClient : public EmptyChromeClient {
  public:
   TooltipCapturingChromeClient() {}