Instant: Don't allow the page to set suggestions inappropriately.

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 1126 matching lines @@
       !last_omnibox_text_.empty();
   if (!can_use_instant_tab && !can_use_overlay)
     return;
 
   if (suggestion.behavior == INSTANT_COMPLETE_REPLACE) {
     // We don't get an Update() when changing the omnibox due to a REPLACE
     // suggestion (so that we don't inadvertently cause the overlay to change
     // what it's showing, as the user arrows up/down through the page-provided
     // suggestions). So, update these state variables here.
     last_omnibox_text_ = suggestion.text;
+    last_user_text_.clear();
     last_suggestion_ = InstantSuggestion();
     last_match_was_search_ = suggestion.type == INSTANT_SUGGESTION_SEARCH;
     LOG_INSTANT_DEBUG_EVENT(this, base::StringPrintf(
         "ReplaceSuggestion text='%s' type=%d",
         UTF16ToUTF8(suggestion.text).c_str(), suggestion.type));
     browser_->SetInstantSuggestion(suggestion);
   } else {
     if (FixSuggestion(&suggestion)) {
       last_suggestion_ = suggestion;
       if (suggestion.type == INSTANT_SUGGESTION_SEARCH &&
@@ skipping 392 matching lines @@
     ntp_->SendMostVisitedItems(items);
   if (instant_tab_)
     instant_tab_->SendMostVisitedItems(items);
   content::NotificationService::current()->Notify(
       chrome::NOTIFICATION_INSTANT_SENT_MOST_VISITED_ITEMS,
       content::Source<InstantController>(this),
       content::NotificationService::NoDetails());
 }
 
 bool InstantController::FixSuggestion(InstantSuggestion* suggestion) const {
+  // We only accept suggestions if the user has typed text. If the user is
+  // arrowing up/down (|last_user_text_| is empty), we reject suggestions.
+  if (last_user_text_.empty())
+    return false;
+
   // If the page is trying to set inline autocompletion in verbatim mode,
   // instead try suggesting the exact omnibox text. This makes the omnibox
   // interpret user text as an URL if possible while preventing unwanted
   // autocompletion during backspacing.
   if (suggestion->behavior == INSTANT_COMPLETE_NOW && last_verbatim_)
     suggestion->text = last_omnibox_text_;
 
   // Suggestion text should be a full URL for URL suggestions, or the
   // completion of a query for query suggestions.
   if (suggestion->type == INSTANT_SUGGESTION_URL) {
@@ skipping 54 matching lines @@
     return false;
 
   // If this is not window startup, switch.
   // TODO(shishir): This is not completely reliable. Find a better way to detect
   // startup time.
   if (browser_->GetActiveWebContents())
     return true;
 
   return chrome::IsAggressiveLocalNTPFallbackEnabled();
 }
-