Instant: Don't use Instant NTP in incognito.

chrome/browser/ui/search/instant_controller.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/search/instant_controller.h"
 
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
@@ skipping 1261 matching lines @@
     CommitIfPossible(INSTANT_COMMIT_FOCUS_LOST);
   else if (!IsViewInContents(GetViewGainingFocus(view_gaining_focus),
                              overlay_->contents()))
     HideOverlay();
 #endif
 }
 
 void InstantController::ResetNTP(bool ignore_blacklist) {
   ntp_.reset();
   std::string instant_url;
-  if (!GetInstantURL(browser_->profile(), ignore_blacklist, &instant_url)) {
+  if (browser_->profile()->IsOffTheRecord() ||
+      !GetInstantURL(browser_->profile(), ignore_blacklist, &instant_url)) {
     // TODO(sreeram|samarth): use local ntp here once available.
     return;
   }
   ntp_.reset(new InstantNTP(this, instant_url));
   ntp_->InitContents(browser_->profile(), browser_->GetActiveWebContents(),
                      base::Bind(&InstantController::ResetNTP,
                                 base::Unretained(this), false));
 }
 
 bool InstantController::EnsureOverlayIsCurrent(bool ignore_blacklist) {
@@ skipping 330 matching lines @@
       // for instance, if the user types 'i' and the suggestion is 'INSTANT',
       // suggest 'nstant'. Otherwise, the user text really isn't a prefix, so
       // suggest nothing.
       // TODO(samarth|jered): revisit this logic. http://crbug.com/196572.
       return true;
     }
   }
 
   return false;
 }