Add metrics for app banner preventDefault() and prompt().

chrome/browser/banners/app_banner_metrics.h

 // Copyright 2015 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_BANNERS_APP_BANNER_METRICS_H_
 #define CHROME_BROWSER_BANNERS_APP_BANNER_METRICS_H_
 
 namespace banners {
 
-// Keep in sync with the values defined in histograms.xml.
+// This enum backs a UMA histogram, so it should be treated as append-only.
 enum DisplayEvent {
   DISPLAY_EVENT_MIN = 0,
   DISPLAY_EVENT_BANNER_REQUESTED = 1,
   DISPLAY_EVENT_BLOCKED_PREVIOUSLY = 2,
   DISPLAY_EVENT_PROMOTED_TOO_MANY_OTHERS = 3,
   DISPLAY_EVENT_CREATED = 4,
   DISPLAY_EVENT_INSTALLED_PREVIOUSLY = 5,
   DISPLAY_EVENT_IGNORED_PREVIOUSLY = 6,
   DISPLAY_EVENT_LACKS_SERVICE_WORKER = 7,
   DISPLAY_EVENT_NOT_VISITED_ENOUGH = 8,
   DISPLAY_EVENT_NATIVE_APP_BANNER_REQUESTED = 9,
   DISPLAY_EVENT_WEB_APP_BANNER_REQUESTED = 10,
   DISPLAY_EVENT_NATIVE_APP_BANNER_CREATED = 11,
   DISPLAY_EVENT_WEB_APP_BANNER_CREATED = 12,
   DISPLAY_EVENT_MAX = 13,
 };
 
+// This enum backs a UMA histogram, so it should be treated as append-only.
 enum InstallEvent {
   INSTALL_EVENT_MIN = 20,
   INSTALL_EVENT_NATIVE_APP_INSTALL_TRIGGERED = 21,
   INSTALL_EVENT_NATIVE_APP_INSTALL_STARTED = 22,
   INSTALL_EVENT_NATIVE_APP_INSTALL_COMPLETED = 23,
   INSTALL_EVENT_WEB_APP_INSTALLED = 24,
   INSTALL_EVENT_MAX = 25,
 };
 
+// This enum backs a UMA histogram, so it should be treated as append-only.
 enum DismissEvent {
   DISMISS_EVENT_MIN = 40,
   DISMISS_EVENT_ERROR = 41,
   DISMISS_EVENT_APP_OPEN = 42,
   DISMISS_EVENT_BANNER_CLICK = 43,
   DISMISS_EVENT_BANNER_SWIPE = 44,
   DISMISS_EVENT_CLOSE_BUTTON = 45,
   DISMISS_EVENT_INSTALL_TIMEOUT = 46,
   DISMISS_EVENT_DISMISSED = 47,
   DISMISS_EVENT_MAX = 48,
 };
 
+// This enum backs a UMA histogram, so it should be treated as append-only.
 enum UserResponse {
   USER_RESPONSE_MIN = 0,
   USER_RESPONSE_NATIVE_APP_ACCEPTED = 1,
   USER_RESPONSE_WEB_APP_ACCEPTED = 2,
   USER_RESPONSE_NATIVE_APP_DISMISSED = 3,
   USER_RESPONSE_WEB_APP_DISMISSED = 4,
   USER_RESPONSE_NATIVE_APP_IGNORED = 5,
   USER_RESPONSE_WEB_APP_IGNORED = 6,
   USER_RESPONSE_MAX = 7,
 };
 
+// This enum backs a UMA histogram, so it should be treated as append-only.
+enum BeforeInstallEvent {
+  BEFORE_INSTALL_EVENT_MIN = 0,
+  BEFORE_INSTALL_EVENT_CREATED = 1,
+  BEFORE_INSTALL_EVENT_COMPLETE = 2,
+  BEFORE_INSTALL_EVENT_NO_ACTION = 3,
+  BEFORE_INSTALL_EVENT_PREVENT_DEFAULT_CALLED = 4,
+  BEFORE_INSTALL_EVENT_PROMPT_CALLED_AFTER_PREVENT_DEFAULT = 5,
+  BEFORE_INSTALL_EVENT_PROMPT_NOT_CALLED_AFTER_PREVENT_DEFAULT = 6,
+  BEFORE_INSTALL_EVENT_MAX = 7,
+};
+
 extern const char kDismissEventHistogram[];
 extern const char kDisplayEventHistogram[];
 extern const char kInstallEventHistogram[];
 extern const char kMinutesHistogram[];
 extern const char kUserResponseHistogram[];
+extern const char kBeforeInstallEventHistogram[];
 
 void TrackDismissEvent(int event);
 void TrackDisplayEvent(int event);
 void TrackInstallEvent(int event);
 void TrackMinutesFromFirstVisitToBannerShown(int minutes);
 void TrackUserResponse(int event);
+void TrackBeforeInstallEvent(int event);
 
 };  // namespace banners
 
 #endif  // CHROME_BROWSER_BANNERS_APP_BANNER_METRICS_H_