Add support for latency measurement to Telemetry smoothness benchmarks.

content/common/browser_rendering_stats.cc

+// Copyright (c) 2013 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 "content/common/browser_rendering_stats.h"
+
+namespace content {
+
+BrowserRenderingStats::BrowserRenderingStats() : input_event_count(0) {}
+
+BrowserRenderingStats::~BrowserRenderingStats() {}
+
+void BrowserRenderingStats::EnumerateFields(
+    cc::RenderingStats::Enumerator* enumerator) const {
+  enumerator->AddInt("inputEventCount", input_event_count);
+  enumerator->AddTimeDeltaInSecondsF("totalInputLatency", total_input_latency);
+}
+
+}  // namespace content