Make some things truly const in SiteEngagementScore.

As it so happens, const char* is only mostly const.

Change-Id: I240167c3fb0545356e15e341b73502770de10ed6
Reviewed-on: https://chromium-review.googlesource.com/575107Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487356}

chrome/browser/engagement/site_engagement_score.cc

@@ -58,10 +58,10 @@ std::unique_ptr<base::DictionaryValue> GetScoreDictForSettings(
 
 const double SiteEngagementScore::kMaxPoints = 100;
 
-const char* SiteEngagementScore::kRawScoreKey = "rawScore";
-const char* SiteEngagementScore::kPointsAddedTodayKey = "pointsAddedToday";
-const char* SiteEngagementScore::kLastEngagementTimeKey = "lastEngagementTime";
-const char* SiteEngagementScore::kLastShortcutLaunchTimeKey =
+const char SiteEngagementScore::kRawScoreKey[] = "rawScore";
+const char SiteEngagementScore::kPointsAddedTodayKey[] = "pointsAddedToday";
+const char SiteEngagementScore::kLastEngagementTimeKey[] = "lastEngagementTime";
+const char SiteEngagementScore::kLastShortcutLaunchTimeKey[] =
     "lastShortcutLaunchTime";
 
 // static

chrome/browser/engagement/site_engagement_score.h

@@ -192,10 +192,10 @@ class SiteEngagementScore {
   static ParamValues BuildParamValues();
 
   // Keys used in the content settings dictionary.
-  static const char* kRawScoreKey;
-  static const char* kPointsAddedTodayKey;
-  static const char* kLastEngagementTimeKey;
-  static const char* kLastShortcutLaunchTimeKey;
+  static const char kRawScoreKey[];
+  static const char kPointsAddedTodayKey[];
+  static const char kLastEngagementTimeKey[];
+  static const char kLastShortcutLaunchTimeKey[];
 
   // This version of the constructor is used in unit tests.
   SiteEngagementScore(base::Clock* clock,