Splitting up RenderWidgetHostLatencyTracker and some renames.

ui/latency/latency_tracker.h

+// Copyright 2017 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.
+
+#ifndef UI_LATENCY_LATENCY_TRACKER_H_
+#define UI_LATENCY_LATENCY_TRACKER_H_
+
+#include <stdint.h>

[tdresser, 2017/04/10 16:15:54]

Is this used?

[mfomitchev, 2017/04/10 19:00:07]

Removed

+
+#include <vector>

[tdresser, 2017/04/10 16:15:54]

Is this used?

[mfomitchev, 2017/04/10 19:00:07]

Removed

+
+#include "base/macros.h"
+#include "ui/latency/latency_info.h"
+
+namespace ui {
+
+// Utility class for tracking the latency of events.
+class LatencyTracker {

[tdresser, 2017/04/10 16:15:54]

Should we split up the RenderWidgetHostLatencyTracker unit tests?

[mfomitchev, 2017/04/10 19:00:07]

All the unit tests I see that test OnGpuSwapBuffersCompleted also use
OnInputEvent and OnInputEventAck, so they are not easily splittable. We could
create a test for OnGpuSwapBuffersCompleted and fake out
OnInputEvent/OnInputEventAck in OnGpuSwapBuffersCompleted, but will not real
give us more coverage, while is a non-trivial amount of work, so it doesn't seem
too useful to me.

+ public:
+  LatencyTracker() = default;
+  ~LatencyTracker() = default;
+
+  // Terminates latency tracking for events that triggered rendering, also
+  // performing relevant UMA latency reporting.
+  // Called when GPU buffers swap completes.
+  void OnGpuSwapBuffersCompleted(const LatencyInfo& latency);
+
+ protected:
+  virtual void ReportRapporScrollLatency(
+      const std::string& name,
+      const LatencyInfo::LatencyComponent& start_component,
+      const LatencyInfo::LatencyComponent& end_component);
+
+ private:
+  void ComputeTouchAndWheelScrollLatencyHistograms(
+      const LatencyInfo::LatencyComponent& gpu_swap_begin_component,
+      const LatencyInfo::LatencyComponent& gpu_swap_end_component,
+      const LatencyInfo& latency);
+
+  DISALLOW_COPY_AND_ASSIGN(LatencyTracker);
+};
+
+}  // namespace latency
+
+#endif  // UI_LATENCY_LATENCY_TRACKER_H_