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..2e225ca1401d9a617ac0af124d0bf1768be40eaa 100644
--- a/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandlerTest.cpp
@@ -16,6 +16,8 @@
 #include "core/page/AutoscrollController.h"
 #include "core/page/Page.h"
 #include "core/testing/DummyPageHolder.h"
+#include "platform/testing/HistogramTester.h"
+#include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
@@ -461,6 +463,87 @@ TEST_F(EventHandlerTest, dragEndInNewDrag) {
   // This test passes if it doesn't crash.
 }
 
+TEST_F(EventHandlerTest, MainThreadScrollingReasonRecordTest) {
+  HistogramTester histogramTester;
+  // Test wheel scroll
+  ScrollManager* scrollManager = new ScrollManager(*(document().frame()));
+  scrollManager->recordMainThreadScrollingReasons(
+      MainThreadScrollingReason::kHasBackgroundAttachmentFixedObjects |
+          MainThreadScrollingReason::kThreadedScrollingDisabled |
+          MainThreadScrollingReason::kPageOverlay |
+          MainThreadScrollingReason::kHandlingScrollFromMainThread,
+      WebGestureDeviceTouchpad);
+
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 1,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 3,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 5,
+                                    1);
+
+  // We only want to record "Handling scroll from main thread" reason if it's
+  // the only reason. If it's not the only reason, the "real" reason for
+  // scrolling on main is something else, and we only want to pay attention to
+  // that reason. So we should only include this reason in the histogram when
+  // its on its own.
+  scrollManager->recordMainThreadScrollingReasons(
+      MainThreadScrollingReason::kHandlingScrollFromMainThread,
+      blink::WebGestureDeviceTouchpad);
+
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 1,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 3,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 5,
+                                    1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 14,
+                                    1);
+
+  scrollManager->recordMainThreadScrollingReasons(
+      MainThreadScrollingReason::kHasBackgroundAttachmentFixedObjects |
+          MainThreadScrollingReason::kThreadedScrollingDisabled |
+          MainThreadScrollingReason::kPageOverlay |
+          MainThreadScrollingReason::kHandlingScrollFromMainThread,
+      WebGestureDeviceTouchpad);
+
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 1,
+                                    2);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 3,
+                                    2);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 5,
+                                    2);
+  histogramTester.expectBucketCount("Renderer4.MainThreadWheelScrollReason", 14,
+                                    1);
+
+  // Test touch scroll
+  scrollManager->recordMainThreadScrollingReasons(
+      MainThreadScrollingReason::kHasBackgroundAttachmentFixedObjects |
+          MainThreadScrollingReason::kThreadedScrollingDisabled |
+          MainThreadScrollingReason::kPageOverlay |
+          MainThreadScrollingReason::kHandlingScrollFromMainThread,
+      WebGestureDeviceTouchscreen);
+
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    1, 1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    3, 1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    5, 1);
+
+  scrollManager->recordMainThreadScrollingReasons(
+      MainThreadScrollingReason::kHandlingScrollFromMainThread,
+      blink::WebGestureDeviceTouchscreen);
+
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    1, 1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    3, 1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    5, 1);
+  histogramTester.expectBucketCount("Renderer4.MainThreadGestureScrollReason",
+                                    14, 1);
+}
+
 class TooltipCapturingChromeClient : public EmptyChromeClient {
  public:
   TooltipCapturingChromeClient() {}