Remove search::GetSearchTerms since it always returns empty string

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 <stddef.h>
 #include <utility>
 
 #include "base/location.h"
@@ skipping 16 matching lines @@
 
 namespace {
 
 bool IsContentsFrom(const InstantTab* page,
                     const content::WebContents* contents) {
   return page && (page->web_contents() == contents);
 }
 
 // Adds a transient NavigationEntry to the supplied |contents|'s
 // NavigationController if the page's URL has not already been updated with the
-// supplied |search_terms|. Sets the |search_terms| on the transient entry for
-// search terms extraction to work correctly.
+// supplied |search_terms|.
+// TODO(treib): Is it safe to completely remove this? crbug.com/627747

[Peter Kasting, 2016/08/13 05:03:44]

Probably?  Not sure, you'd need to check with kmadhusu or someone else more
knowledgeable.  But at a glance it looks as if this is only really needed to
expose the search terms, which I think you're ripping out the readers of.

[Marc Treib, 2016/08/16 12:00:17]

Yup, that's my feeling too, but just to be safe I decided to defer this to
another CL - it's at least conceivable that creating this transient entry has
some other side-effects that someone depends on.

 void EnsureSearchTermsAreSet(content::WebContents* contents,
                              const base::string16& search_terms) {
   content::NavigationController* controller = &contents->GetController();
 
   // If search terms are already correct or there is already a transient entry
   // (there shouldn't be), bail out early.
-  if (search::GetSearchTerms(contents) == search_terms ||
-      controller->GetTransientEntry())
+  if (search_terms.empty() || controller->GetTransientEntry())
     return;
 
   const content::NavigationEntry* entry = controller->GetLastCommittedEntry();
   std::unique_ptr<content::NavigationEntry> transient =
       controller->CreateNavigationEntry(
           entry->GetURL(), entry->GetReferrer(), entry->GetTransitionType(),
           false, std::string(), contents->GetBrowserContext());
-  transient->SetExtraData(sessions::kSearchTermsKey, search_terms);
   controller->SetTransientEntry(std::move(transient));
 
   SearchTabHelper::FromWebContents(contents)->NavigationEntryUpdated();
 }
 
 }  // namespace
 
 InstantController::InstantController(BrowserInstantController* browser)
     : browser_(browser) {
 }
@@ skipping 104 matching lines @@
     if (instant_service) {
       instant_service->UpdateThemeInfo();
       instant_service->UpdateMostVisitedItemsInfo();
     }
   }
 }
 
 InstantService* InstantController::GetInstantService() const {
   return InstantServiceFactory::GetForProfile(browser_->profile());
 }