Discard ChromeViewHostMsg_SearchBox* IPCs if they not sent from an Instant process.

chrome/browser/search/search.h

Index: chrome/browser/search/search.h
diff --git a/chrome/browser/search/search.h b/chrome/browser/search/search.h
index 978e394903849d5b0744778b735165d0205e8673..d8c2cdd6a5a9af1e11b8a7d47fd63f9460ba83ec 100644
--- a/chrome/browser/search/search.h
+++ b/chrome/browser/search/search.h
@@ -121,6 +121,11 @@ base::string16 GetSearchTerms(const content::WebContents* contents);
 // Returns true if |url| should be rendered in the Instant renderer process.
 bool ShouldAssignURLToInstantRenderer(const GURL& url, Profile* profile);
 
+// Returns true if |contents| is rendered inside the Instant process for
+// |profile|.
+bool IsRenderedInInstantProcess(const content::WebContents* contents,
+                                Profile* profile);
+
 // Returns true if the Instant |url| should use process per site.
 bool ShouldUseProcessPerSiteForInstantURL(const GURL& url, Profile* profile);