Log First User Interaction in Page Load Metrics

content/browser/renderer_host/input/render_widget_host_latency_tracker.cc

 // Copyright 2014 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/browser/renderer_host/input/render_widget_host_latency_tracker.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 287 matching lines @@
   DCHECK_EQ(0, last_event_id_);
   DCHECK_EQ(0, latency_component_id_);
   last_event_id_ = static_cast<int64_t>(process_id) << 32;
   latency_component_id_ = routing_id | last_event_id_;
 }
 
 void RenderWidgetHostLatencyTracker::OnInputEvent(
     const blink::WebInputEvent& event,
     LatencyInfo* latency) {
   DCHECK(latency);
+
+  for (size_t i = 0; i < input_event_callbacks_.size(); ++i) {
+    input_event_callbacks_[i].Run(event);
+  }
+
   if (latency->FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
                            latency_component_id_, NULL)) {
     return;
   }
 
   if (event.timeStampSeconds &&
       !latency->FindLatency(ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
                             0, NULL)) {
     base::TimeTicks timestamp_now = base::TimeTicks::Now();
     base::TimeTicks timestamp_original = base::TimeTicks() +
@@ skipping 145 matching lines @@
   if (!latency.FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
                            latency_component_id_, nullptr)) {
     return;
   }
 
   ComputeScrollLatencyHistograms(gpu_swap_begin_component,
                                  gpu_swap_end_component, latency_component_id_,
                                  latency);
 }
 
+void RenderWidgetHostLatencyTracker::AddInputEventCallback(
+    const InputEventCallback& callback) {
+  input_event_callbacks_.push_back(callback);
+}
+
+void RenderWidgetHostLatencyTracker::RemoveInputEventCallback(
+    const InputEventCallback& callback) {
+  for (size_t i = 0; i < input_event_callbacks_.size(); ++i) {
+    if (input_event_callbacks_[i].Equals(callback)) {
+      input_event_callbacks_.erase(input_event_callbacks_.begin() + i);
+      return;
+    }
+  }
+}
+
 }  // namespace content