Enable SiteEngagementEvictionPolicy behind --enable-site-eviction-policy flag.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 2789d6a7efc6d613a37d8e7eee910c6d5c0cd4d4..9751b3914ec5263725ef6ef8d9a0f77afb6789e9 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -531,6 +531,12 @@ const char kEnableSimplifiedFullscreenUI[]  = "enable-simplified-fullscreen-ui";
 const char kDisableSimplifiedFullscreenUI[] =
     "disable-simplified-fullscreen-ui";
 
+// Enable the Site Engagement Eviction Policy which evicts temporary storage
+// using the site engagement service. Implicitly enables the site engagement
+// service.
+const char kEnableSiteEngagementEvictionPolicy[] =
+    "enable-site-engagement-eviction-policy";
+
 // Enable the Site Engagement service, which records interaction with sites and
 // allocates certain resources accordingly.
 const char kEnableSiteEngagementService[]   = "enable-site-engagement-service";