Record the fraction of the time without user input - Aura only

ui/events/fraction_of_time_without_user_input_recorder.cc

Index: ui/events/fraction_of_time_without_user_input_recorder.cc
diff --git a/ui/events/fraction_of_time_without_user_input_recorder.cc b/ui/events/fraction_of_time_without_user_input_recorder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..63026261b823fef05a26269ba7e72a4151a69166
--- /dev/null
+++ b/ui/events/fraction_of_time_without_user_input_recorder.cc
@@ -0,0 +1,80 @@
+// 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.
+
+#include "ui/events/fraction_of_time_without_user_input_recorder.h"
+
+#include <algorithm>
+
+#include "base/metrics/histogram_macros.h"
+
+namespace {
+
+constexpr base::TimeDelta DEFAULT_WINDOW_SIZE =
+    base::TimeDelta::FromSecondsD(10);
+constexpr base::TimeDelta DEFAULT_IDLE_TIMEOUT =
+    base::TimeDelta::FromSecondsD(0.05);
+
+}  // namespace
+
+namespace ui {
+
+FractionOfTimeWithoutUserInputRecorder::FractionOfTimeWithoutUserInputRecorder()
+    : window_size_(DEFAULT_WINDOW_SIZE), idle_timeout_(DEFAULT_IDLE_TIMEOUT) {}
+
+void FractionOfTimeWithoutUserInputRecorder::RecordEventAtTime(
+    base::TimeTicks start_time) {
+  base::TimeTicks event_end_time = start_time + idle_timeout_;
+
+  if (active_duration_start_time_.is_null())
+    active_duration_start_time_ = start_time;
+  if (previous_event_end_time_.is_null())
+    previous_event_end_time_ = start_time;
+
+  // The user is no longer interacting with the browser. Report the previous
+  // active duration.
+  if (previous_event_end_time_ < start_time) {
+    RecordActiveInterval(active_duration_start_time_, previous_event_end_time_);
+    active_duration_start_time_ = start_time;
+  }
+
+  previous_event_end_time_ = event_end_time;
+}
+
+void FractionOfTimeWithoutUserInputRecorder::RecordActiveInterval(
+    base::TimeTicks start_time,
+    base::TimeTicks end_time) {
+  if (window_start_time_.is_null())
+    window_start_time_ = start_time;
+
+  base::TimeTicks window_end_time;
+
+  while (true) {
+    window_end_time = window_start_time_ + window_size_;
+    base::TimeDelta interval_in_window_duration =
+        std::min(end_time, window_end_time) -
+        std::max(start_time, window_start_time_);
+    interval_in_window_duration =
+        std::max(interval_in_window_duration, base::TimeDelta());
+
+    current_window_active_time_ += interval_in_window_duration;
+
+    // If we haven't exceeded the window bounds, we're done.
+    if (end_time < window_end_time)
+      break;
+
+    RecordToUma(current_window_active_time_.InMillisecondsF() /
+                window_size_.InMillisecondsF());
+
+    current_window_active_time_ = base::TimeDelta();
+    window_start_time_ = window_end_time;
+  }
+}
+
+void FractionOfTimeWithoutUserInputRecorder::RecordToUma(
+    float fraction_active) const {
+  UMA_HISTOGRAM_PERCENTAGE("Event.FractionOfTimeWithoutUserInput",
+                           std::round((1 - fraction_active) * 100));
+}
+
+}  // namespace ui