Add WebAPK installation metrics.

chrome/browser/android/webapk/webapk_metrics.h

+// 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.
+
+#ifndef CHROME_BROWSER_ANDROID_WEBAPK_WEBAPK_METRICS_H_
+#define CHROME_BROWSER_ANDROID_WEBAPK_WEBAPK_METRICS_H_
+
+#include "base/macros.h"
+
+namespace webapk {
+
+// The states of WebAPK installation process. These states are tracked to
+// record dismiss events for WebAPK installation.
+enum InstallState {
+  WAIT_FOR_START,
+  INSTALLING,
+  INSTALLED,
+};
+
+// Keep these enums up to date with tools/metrics/histograms/histograms.xml.
+// The sum of |InstalllEvent| histogram is the total number of times that a
+// WebAPK infobar was triggered.
+enum InstallEvent {
+  // Banner is deleted due to the closing of Chrome or the associated tab.
+  INSTALL_EVENT_BANNER_IGNORED = 0,
+  // The banner with the "Add-to-Homescreen" button is dismissed before the
+  // installation stared. The *_DISMISS events are the cases that user
+  // closes the banner by clicking the "X" button.
+  INSTALL_EVENT_ADD_TO_HOME_SCREEN_DISMISS,
+  // The banner with the "Adding" button is dismissed during installation.
+  INSTALL_EVENT_ADDING_DISMISS,
+  INSTALL_EVENT_COMPLETED,
+  INSTALL_EVENT_FAILED,
+  INSTALL_EVENT_MAX,
+};
+
+enum StartType {
+  TRIGGERED_FROM_BANNER = 0,
+  STARTED_FROM_BANNER,
+  STARTED_FROM_ADD_TO_HOME_SCREEN_MENU,
+  START_TYPE_MAX,
+};
+
+enum UserAction {
+  USER_ACTION_INSTALLED_OPEN = 0,
+  USER_ACTION_INSTALLED_OPEN_DISMISS,
+  USER_ACTION_MAX,
+};
+
+void TrackInstallEvent(InstallEvent event);
+void TrackStartType(StartType event);
+void TrackUserAction(UserAction event);
+
+};  // namespace webapk
+
+#endif  // CHROME_BROWSER_ANDROID_WEBAPK_WEBAPK_METRICS_H_