Use the site engagement eviction policy for temporary storage eviction.

chrome/browser/engagement/site_engagement_service.h

Index: chrome/browser/engagement/site_engagement_service.h
diff --git a/chrome/browser/engagement/site_engagement_service.h b/chrome/browser/engagement/site_engagement_service.h
index 60644a4a4e3f504721d10a8a2e0666eb635dac34..77223868b5dc4a278df873868752cf1e86d703d1 100644
--- a/chrome/browser/engagement/site_engagement_service.h
+++ b/chrome/browser/engagement/site_engagement_service.h
@@ -7,6 +7,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time/default_clock.h"
 #include "base/time/time.h"
 #include "components/keyed_service/core/keyed_service.h"
@@ -17,6 +18,7 @@ class DictionaryValue;
 
 class GURL;
 class Profile;
+class SiteEngagementEvictionPolicy;
 
 class SiteEngagementScore {
  public:
@@ -108,7 +110,8 @@ class SiteEngagementService : public KeyedService,
  public:
   static SiteEngagementService* Get(Profile* profile);
 
-  // Returns whether or not the SiteEngagementService is enabled.
+  // Returns whether or not the SiteEngagementService is enabled. Enabling
+  // dependent features will cause this to return true.
   static bool IsEnabled();
 
   explicit SiteEngagementService(Profile* profile);
@@ -117,6 +120,10 @@ class SiteEngagementService : public KeyedService,
   // Update the karma score of the origin matching |url| for user navigation.
   void HandleNavigation(const GURL& url);
 
+  SiteEngagementEvictionPolicy* site_engagement_eviction_policy() {
+    return site_engagement_eviction_policy_.get();
+  }
+
   // Overridden from SiteEngagementScoreProvider:
   int GetScore(const GURL& url) override;
   int GetTotalEngagementPoints() override;
@@ -124,6 +131,8 @@ class SiteEngagementService : public KeyedService,
  private:
   Profile* profile_;
 
+  scoped_ptr<SiteEngagementEvictionPolicy> site_engagement_eviction_policy_;
+
   // The clock used to vend times.
   base::DefaultClock clock_;