[Android] Add AppMenu touch duration metric.

chrome/browser/android/appmenu/app_menu_drag_helper.cc

Index: chrome/browser/android/appmenu/app_menu_drag_helper.cc
diff --git a/chrome/browser/android/appmenu/app_menu_drag_helper.cc b/chrome/browser/android/appmenu/app_menu_drag_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1a6bdce57cda49a18505f064b95da2362de3d06b
--- /dev/null
+++ b/chrome/browser/android/appmenu/app_menu_drag_helper.cc
@@ -0,0 +1,22 @@
+// 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 "base/metrics/histogram_macros.h"
+#include "chrome/browser/android/appmenu/app_menu_drag_helper.h"
+#include "jni/AppMenuDragHelper_jni.h"
+
+namespace appmenu {

[Ted C, 2014/12/10 17:28:55]

These namespaces are way too specific.  I think in the chrome package, they are
promoting the removal of all namespaces, so I think you can just drop these (and
maybe make the name RecordAppMenuTouchDuration for name collision prevention).

[Kibeom Kim (inactive), 2014/12/15 22:14:30]

Done.

+namespace android {
+
+bool RegisterAppMenuDragHelper(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+void RecordTouchDuration(JNIEnv* env, jclass jcaller, jlong time_ms) {

[Ted C, 2014/12/10 17:28:55]

add "// static" above this.

[Kibeom Kim (inactive), 2014/12/15 22:14:30]

Done.

+  UMA_HISTOGRAM_TIMES("AppMenu.TouchDuration",
+                      base::TimeDelta::FromMilliseconds(time_ms));
+}
+
+}  // namespace android
+}  // namespace appmenu