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

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/input/ScrollManager.h"
 
 #include <memory>
 #include "core/dom/DOMNodeIds.h"
 #include "core/events/GestureEvent.h"
 #include "core/frame/BrowserControls.h"
 #include "core/frame/FrameView.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/input/EventHandler.h"
 #include "core/input/EventHandlingUtil.h"
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutPart.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/Page.h"
 #include "core/page/scrolling/OverscrollController.h"
 #include "core/page/scrolling/RootScrollerController.h"
 #include "core/page/scrolling/ScrollState.h"
 #include "core/paint/PaintLayer.h"
+#include "platform/Histogram.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
 ScrollManager::ScrollManager(LocalFrame& frame) : frame_(frame) {
   Clear();
 }
 
 void ScrollManager::Clear() {
@@ skipping 154 matching lines @@
   if (scroll_state.deltaX() || scroll_state.deltaY())
     frame_->GetDocument()->UpdateStyleAndLayoutIgnorePendingStylesheets();
 
   if (current_scroll_chain_.empty())
     RecomputeScrollChain(start_node, current_scroll_chain_);
   scroll_state.SetScrollChain(current_scroll_chain_);
 
   scroll_state.distributeToScrollChainDescendant();
 }
 
+uint32_t ScrollManager::ComputeNonCompositedMainThreadScrollingReasons() {
+  // When scrolling on the main thread, the scrollableArea may or may not be
+  // composited. Either way, we have recorded either the reasons stored in
+  // its layer or the reason NonFastScrollableRegion from the compositor
+  // side. Here we record scrolls that occurred on main thread due to a
+  // non-composited scroller.
+  if (!scroll_gesture_handling_node_->GetLayoutObject() || !frame_->View())
+    return 0;
+
+  uint32_t non_composited_main_thread_scrolling_reasons = 0;
+
+  for (auto* cur_box =
+           scroll_gesture_handling_node_->GetLayoutObject()->EnclosingBox();
+       cur_box; cur_box = cur_box->ContainingBlock()) {
+    PaintLayerScrollableArea* scrollable_area = cur_box->GetScrollableArea();
+
+    if (!scrollable_area || !scrollable_area->ScrollsOverflow())
+      continue;
+
+    DCHECK(!scrollable_area->UsesCompositedScrolling() ||
+           !scrollable_area->GetNonCompositedMainThreadScrollingReasons());
+    non_composited_main_thread_scrolling_reasons |=
+        scrollable_area->GetNonCompositedMainThreadScrollingReasons();
+  }
+
+  return non_composited_main_thread_scrolling_reasons;
+}
+
+void ScrollManager::RecordNonCompositedMainThreadScrollingReasons(
+    const WebGestureDevice device) {
+  if (device != kWebGestureDeviceTouchpad &&
+      device != kWebGestureDeviceTouchscreen) {
+    return;
+  }
+
+  uint32_t reasons = ComputeNonCompositedMainThreadScrollingReasons();
+  if (!reasons)
+    return;
+  DCHECK(MainThreadScrollingReason::HasNonCompositedScrollReasons(reasons));
+
+  uint32_t main_thread_scrolling_reason_enum_max =
+      MainThreadScrollingReason::kMainThreadScrollingReasonCount + 1;
+  for (uint32_t i = MainThreadScrollingReason::kNonCompositedReasonsFirst;
+       i <= MainThreadScrollingReason::kNonCompositedReasonsLast; ++i) {
+    unsigned val = 1 << i;
+    if (reasons & val) {
+      if (device == kWebGestureDeviceTouchscreen) {
+        DEFINE_STATIC_LOCAL(EnumerationHistogram, touch_histogram,
+                            ("Renderer4.MainThreadGestureScrollReason",
+                             main_thread_scrolling_reason_enum_max));
+        touch_histogram.Count(i + 1);
+      } else {
+        DEFINE_STATIC_LOCAL(EnumerationHistogram, wheel_histogram,
+                            ("Renderer4.MainThreadWheelScrollReason",
+                             main_thread_scrolling_reason_enum_max));
+        wheel_histogram.Count(i + 1);
+      }
+    }
+  }
+}
+
 WebInputEventResult ScrollManager::HandleGestureScrollBegin(
     const WebGestureEvent& gesture_event) {
   Document* document = frame_->GetDocument();
 
   if (document->GetLayoutViewItem().IsNull())
     return WebInputEventResult::kNotHandled;
 
   // If there's no layoutObject on the node, send the event to the nearest
   // ancestor with a layoutObject.  Needed for <option> and <optgroup> elements
   // so we can touch scroll <select>s
   while (scroll_gesture_handling_node_ &&
          !scroll_gesture_handling_node_->GetLayoutObject())
     scroll_gesture_handling_node_ =
         scroll_gesture_handling_node_->ParentOrShadowHostNode();
 
   if (!scroll_gesture_handling_node_)
     scroll_gesture_handling_node_ = frame_->GetDocument()->documentElement();
 
   if (!scroll_gesture_handling_node_ ||
       !scroll_gesture_handling_node_->GetLayoutObject())
     return WebInputEventResult::kNotHandled;
 
   PassScrollGestureEvent(gesture_event,
                          scroll_gesture_handling_node_->GetLayoutObject());
 
+  RecordNonCompositedMainThreadScrollingReasons(gesture_event.source_device);
+
   current_scroll_chain_.clear();
   std::unique_ptr<ScrollStateData> scroll_state_data =
       WTF::MakeUnique<ScrollStateData>();
   IntPoint position = FlooredIntPoint(gesture_event.PositionInRootFrame());
   scroll_state_data->position_x = position.X();
   scroll_state_data->position_y = position.Y();
   scroll_state_data->is_beginning = true;
   scroll_state_data->from_user_input = true;
   scroll_state_data->is_direct_manipulation =
       gesture_event.source_device == kWebGestureDeviceTouchscreen;
@@ skipping 332 matching lines @@
                                 &should_update_capture)) {
       if (should_update_capture)
         scrollbar_handling_scroll_gesture_ = scrollbar;
       return true;
     }
   }
   return false;
 }
 
 }  // namespace blink