Prerender Instant search base url on omnibox focus event

chrome/browser/ui/omnibox/omnibox_edit_model.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/omnibox/omnibox_edit_model.h"
 
 #include <string>
 
 #include "base/auto_reset.h"
 #include "base/format_macros.h"
@@ skipping 350 matching lines @@
   // never actually use it.  This avoids running the autocomplete providers (and
   // any systems they then spin up) during startup.
   const AutocompleteMatch& current_match = user_input_in_progress_ ?
       CurrentMatch(NULL) : AutocompleteMatch();
 
   AutocompleteActionPredictor::Action recommended_action =
       AutocompleteActionPredictor::ACTION_NONE;
   if (user_input_in_progress_) {
     InstantSearchPrerenderer* prerenderer =
         InstantSearchPrerenderer::GetForProfile(profile_);
-    if (prerenderer &&
+    if (prerenderer && !chrome::ShouldPrerenderInstantUrlOnOmniboxFocus() &&

[kmadhusu, 2014/06/18 16:23:50]

We should not add this check here. Consider the following case:

1. Open 2 browser windows.
2. Activate the new tab in browser_window_2. Since the omnibox has focus, we
should have prerendered an Instant search base page.
3. Don't type or switch to other tabs. Wait until the prerender manager times
out this prerendered page.
4. Now type a search query in the omnibox.

Expected behavior: We should have prerendered the Instant search base page and
used it to prefetch search results for the high-confidence query.
Actual behavior: Because of this check, we will never prerender the Instant
search base page after it is timed out.

[sidharthms, 2014/06/19 20:36:52]

Done.

         prerenderer->IsAllowed(current_match, controller_->GetWebContents()) &&
         popup_model()->IsOpen() && has_focus()) {
       recommended_action = AutocompleteActionPredictor::ACTION_PRERENDER;
     } else {
       AutocompleteActionPredictor* action_predictor =
           predictors::AutocompleteActionPredictorFactory::GetForProfile(
               profile_);
       action_predictor->RegisterTransitionalMatches(user_text_, result());
       // Confer with the AutocompleteActionPredictor to determine what action,
       // if any, we should take. Get the recommended action here even if we
@@ skipping 1084 matching lines @@
   // Update state and notify view if the omnibox has focus and the caret
   // visibility changed.
   const bool was_caret_visible = is_caret_visible();
   focus_state_ = state;
   if (focus_state_ != OMNIBOX_FOCUS_NONE &&
       is_caret_visible() != was_caret_visible)
     view_->ApplyCaretVisibility();
 
   delegate_->OnFocusChanged(focus_state_, reason);
 }