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

chrome/browser/ui/search/search_ipc_router.cc

Index: chrome/browser/ui/search/search_ipc_router.cc
diff --git a/chrome/browser/ui/search/search_ipc_router.cc b/chrome/browser/ui/search/search_ipc_router.cc
index 776876c6476dac4ad05d6aa20fbdeb7ef512ac33..889ea9cb4ac4bf829ac4a0938788be8ff38e6d1b 100644
--- a/chrome/browser/ui/search/search_ipc_router.cc
+++ b/chrome/browser/ui/search/search_ipc_router.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/ui/search/search_ipc_router.h"
 
+#include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/common/render_messages.h"
 #include "content/public/browser/navigation_details.h"
@@ -150,6 +151,11 @@ void SearchIPCRouter::OnTabDeactivated() {
 }
 
 bool SearchIPCRouter::OnMessageReceived(const IPC::Message& message) {
+  Profile* profile =
+      Profile::FromBrowserContext(web_contents()->GetBrowserContext());
+  if (!chrome::IsRenderedInInstantProcess(web_contents(), profile))
+    return false;
+
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(SearchIPCRouter, message)
     IPC_MESSAGE_HANDLER(ChromeViewHostMsg_InstantSupportDetermined,