add stylus metrics

ash/wm/stylus_metrics_recorder.cc

Index: ash/wm/stylus_metrics_recorder.cc
diff --git a/ash/wm/stylus_metrics_recorder.cc b/ash/wm/stylus_metrics_recorder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..275295460da558cd3fae876585e1c40235271a75
--- /dev/null
+++ b/ash/wm/stylus_metrics_recorder.cc
@@ -0,0 +1,83 @@
+// Copyright 2016 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 "ash/wm/stylus_metrics_recorder.h"
+
+#include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
+#include "ash/common/wm_shell.h"
+#include "ash/shell.h"
+#include "base/metrics/histogram.h"
+#include "ui/events/event.h"
+#include "ui/events/event_constants.h"
+#include "ui/events/event_utils.h"
+
+namespace ash {
+
+// Form factor of the down event. This enum is used to back an UMA histogram
+// and should be treated as append-only.
+enum DownEventFormFactor {
+  DOWN_EVENT_FORMFACTOR_CLAMSHELL = 0,
+  DOWN_EVENT_FORMFACTOR_TOUCHVIEW,
+  DOWN_EVENT_FORMFACTOR_COUNT
+};
+
+// Input type of the down event. This enum is used to back an UMA histogram
+// and should be treated as append-only.
+enum DownEventSource {
+  DOWN_EVENT_SOURCE_UNKNOWN = 0,
+  DOWN_EVENT_SOURCE_MOUSE,
+  DOWN_EVENT_SOURCE_STYLUS,
+  DOWN_EVENT_SOURCE_TOUCH,
+  DOWN_EVENT_SOURCE_COUNT
+};
+
+StylusMetricsRecorder::StylusMetricsRecorder() {}
+
+StylusMetricsRecorder::~StylusMetricsRecorder() {}
+
+void StylusMetricsRecorder::OnMouseEvent(ui::MouseEvent* event) {
+  if (event->type() != ui::ET_MOUSE_PRESSED)
+    return;
+  RecordUMA(event->pointer_details().pointer_type);
+}
+
+void StylusMetricsRecorder::OnTouchEvent(ui::TouchEvent* event) {
+  if (event->type() != ui::ET_TOUCH_PRESSED)
+    return;
+  RecordUMA(event->pointer_details().pointer_type);
+}
+
+void StylusMetricsRecorder::RecordUMA(ui::EventPointerType type) {
+  DownEventFormFactor form_factor;
+  if (WmShell::Get()
+          ->maximize_mode_controller()
+          ->IsMaximizeModeWindowManagerEnabled()) {
+    form_factor = DOWN_EVENT_FORMFACTOR_TOUCHVIEW;
+  } else {
+    form_factor = DOWN_EVENT_FORMFACTOR_CLAMSHELL;
+  }
+  UMA_HISTOGRAM_ENUMERATION("Event.DownEventCount.PerFormFactor", form_factor,
+                            DOWN_EVENT_FORMFACTOR_COUNT);
+
+  DownEventSource input_type;

[Ilya Sherman, 2016/08/24 00:48:01]

nit: I think the Visual Studio compiler isn't clever enough to realize that the
switch stmt covers all cases, so you'll need to initialize this variable before
the switch stmt -- probably to DOWN_EVENT_SOURCE_UNKNOWN.  This isn't an issue
for clang-based compilers, but unfortunately such is the cost of supporting
multiple toolchains.

[xiaoyinh(OOO Sep 11-29), 2016/08/24 16:51:51]

Done.

+  switch (type) {
+    case ui::EventPointerType::POINTER_TYPE_UNKNOWN:
+      input_type = DOWN_EVENT_SOURCE_UNKNOWN;
+      break;
+    case ui::EventPointerType::POINTER_TYPE_MOUSE:
+      input_type = DOWN_EVENT_SOURCE_MOUSE;
+      break;
+    case ui::EventPointerType::POINTER_TYPE_PEN:
+      input_type = DOWN_EVENT_SOURCE_STYLUS;
+      break;
+    case ui::EventPointerType::POINTER_TYPE_TOUCH:
+      input_type = DOWN_EVENT_SOURCE_TOUCH;
+      break;
+  }
+
+  UMA_HISTOGRAM_ENUMERATION("Event.DownEventCount.PerInput", input_type,
+                            DOWN_EVENT_SOURCE_COUNT);
+}
+
+}  // namespace ash