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

chrome/browser/banners/app_banner_metrics.cc

 // 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.
 
 #include "chrome/browser/banners/app_banner_metrics.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 
 namespace banners {
 
 const char kDismissEventHistogram[] = "AppBanners.DismissEvent";
 const char kDisplayEventHistogram[] = "AppBanners.DisplayEvent";
 const char kInstallEventHistogram[] = "AppBanners.InstallEvent";
 const char kMinutesHistogram[] =
     "AppBanners.MinutesFromFirstVisitToBannerShown";
 const char kUserResponseHistogram[] = "AppBanners.UserResponse";
+const char kBeforeInstallEventHistogram[] = "AppBanners.BeforeInstallEvent";
 
 void TrackDismissEvent(int event) {
   DCHECK_LT(DISMISS_EVENT_MIN, event);
   DCHECK_LT(event, DISMISS_EVENT_MAX);
   UMA_HISTOGRAM_SPARSE_SLOWLY(kDismissEventHistogram, event);
 }
 
 void TrackDisplayEvent(int event) {
   DCHECK_LT(DISPLAY_EVENT_MIN, event);
   DCHECK_LT(event, DISPLAY_EVENT_MAX);
@@ skipping 13 matching lines @@
   // navigation heuristic.
   UMA_HISTOGRAM_CUSTOM_COUNTS(kMinutesHistogram, minutes, 1, 30240, 100);
 }
 
 void TrackUserResponse(int event) {
   DCHECK_LT(USER_RESPONSE_MIN, event);
   DCHECK_LT(event, USER_RESPONSE_MAX);
   UMA_HISTOGRAM_SPARSE_SLOWLY(kUserResponseHistogram, event);
 }
 
+void TrackBeforeInstallEvent(int event) {
+  DCHECK_LT(BEFORE_INSTALL_EVENT_MIN, event);
+  DCHECK_LT(event, BEFORE_INSTALL_EVENT_MAX);
+  UMA_HISTOGRAM_SPARSE_SLOWLY(kBeforeInstallEventHistogram, event);
+}
+
 }  // namespace banners