Use process per site instance for "Instant".

chrome/browser/search/search.cc

Index: chrome/browser/search/search.cc
diff --git a/chrome/browser/search/search.cc b/chrome/browser/search/search.cc
index ec6b19364a4afaf7880cffb0c95dc5c56fe1502d..384b2e75ce82dc02878e282b9a00e51853d8452f 100644
--- a/chrome/browser/search/search.cc
+++ b/chrome/browser/search/search.cc
@@ -296,6 +296,12 @@ bool ShouldAssignURLToInstantRenderer(const GURL& url, Profile* profile) {
           IsInstantURL(url, profile));
 }
 
+bool ShouldInstantURLUseProcessPerSite(const GURL& url, Profile* profile) {
+  return ShouldAssignURLToInstantRenderer(url, profile) &&
+      (url.host() == chrome::kChromeSearchLocalNtpHost ||
+       url.host() == chrome::kChromeSearchOnlineNtpHost);
+}
+
 bool IsInstantNTP(const content::WebContents* contents) {
   if (!contents)
     return false;