Add UseCounters for alert(), confirm() and prompt() usage against site engagement.

third_party/WebKit/Source/core/frame/UseCounter.h

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1383 matching lines @@
     V8PeriodicWave_Constructor = 1721,
     V8StereoPannerNode_Constructor = 1722,
     V8WaveShaperNode_Constructor = 1723,
     V8Headers_GetAll_Method = 1724,
     NavigatorVibrateEngagementNone = 1725,
     NavigatorVibrateEngagementMinimal = 1726,
     NavigatorVibrateEngagementLow = 1727,
     NavigatorVibrateEngagementMedium = 1728,
     NavigatorVibrateEngagementHigh = 1729,
     NavigatorVibrateEngagementMax = 1730,
+    AlertEngagementNone = 1731,
+    AlertEngagementMinimal = 1732,
+    AlertEngagementLow = 1733,
+    AlertEngagementMedium = 1734,
+    AlertEngagementHigh = 1735,
+    AlertEngagementMax = 1736,
+    ConfirmEngagementNone = 1737,
+    ConfirmEngagementMinimal = 1738,
+    ConfirmEngagementLow = 1739,
+    ConfirmEngagementMedium = 1740,
+    ConfirmEngagementHigh = 1741,
+    ConfirmEngagementMax = 1742,
+    PromptEngagementNone = 1743,
+    PromptEngagementMinimal = 1744,
+    PromptEngagementLow = 1745,
+    PromptEngagementMedium = 1746,
+    PromptEngagementHigh = 1747,
+    PromptEngagementMax = 1748,
 
     // Add new features immediately above this line. Don't change assigned
     // numbers of any item, and don't reuse removed slots.
     // Also, run update_use_counter_feature_enum.py in
     // chromium/src/tools/metrics/histograms/ to update the UMA mapping.
     NumberOfFeatures,  // This enum value must be last.
   };
 
   // "count" sets the bit for this feature to 1. Repeated calls are ignored.
   static void count(const Frame*, Feature);
@@ skipping 68 matching lines @@
     // Tracks what features/properties need to be reported to the legacy
     // histograms.
     BitVector m_featureBits;
     BitVector m_CSSBits;
   } m_legacyCounter;
 };
 
 }  // namespace blink
 
 #endif  // UseCounter_h