UMA metrics for use count of wheel and touch scrolls.

cc/trees/layer_tree_host.cc

 // Copyright 2011 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 "cc/trees/layer_tree_host.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 719 matching lines @@
                                    info->elastic_overscroll_delta);
   // TODO(ccameron): pass the elastic overscroll here so that input events
   // may be translated appropriately.
   client_->ApplyViewportDeltas(inner_viewport_scroll_delta, gfx::Vector2dF(),
                                info->elastic_overscroll_delta,
                                info->page_scale_delta,
                                info->top_controls_delta);
   SetNeedsUpdateLayers();
 }
 
+void LayerTreeHost::RecordWheelAndTouchScrollingCount(ScrollAndScaleSet* info) {
+  if (!info || info->scroll_source_info == 0)

[danakj, 2017/03/10 20:52:48]

When will info be null?

[sahel, 2017/03/13 20:13:43]

Done.

+    return;
+
+  bool has_scrolled_by_wheel =
+      (info->scroll_source_info &
+       InputHandler::ScrollSourceInfo::SCROLLED_BY_WHEEL) != 0;
+  bool has_scrolled_by_touch =
+      (info->scroll_source_info &
+       InputHandler::ScrollSourceInfo::SCROLLED_BY_TOUCH) != 0;
+
+  client_->RecordWheelAndTouchScrollingCount(has_scrolled_by_wheel,
+                                             has_scrolled_by_touch);
+}
+
 void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   for (auto& swap_promise : info->swap_promises) {
     TRACE_EVENT_WITH_FLOW1("input,benchmark", "LatencyInfo.Flow",
                            TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
                            TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT,
                            "step", "Main thread scroll update");
     swap_promise_manager_.QueueSwapPromise(std::move(swap_promise));
   }
 
   if (root_layer_) {
@@ skipping 10 matching lines @@
       if (!layer)
         continue;
       layer->SetScrollbarsHiddenFromImplSide(info->scrollbars[i].hidden);
     }
   }
 
   // This needs to happen after scroll deltas have been sent to prevent top
   // controls from clamping the layout viewport both on the compositor and
   // on the main thread.
   ApplyViewportDeltas(info);
+
+  RecordWheelAndTouchScrollingCount(info);
 }
 
 const base::WeakPtr<InputHandler>& LayerTreeHost::GetInputHandler()
     const {
   return input_handler_weak_ptr_;
 }
 
 void LayerTreeHost::UpdateBrowserControlsState(
     BrowserControlsState constraints,
     BrowserControlsState current,
@@ skipping 551 matching lines @@
 LayerListReverseIterator<Layer> LayerTreeHost::rend() {
   return LayerListReverseIterator<Layer>(nullptr);
 }
 
 void LayerTreeHost::SetNeedsDisplayOnAllLayers() {
   for (auto* layer : *this)
     layer->SetNeedsDisplay();
 }
 
 }  // namespace cc