Disables instant preview for search engines that don't support the

instant API.

BUG=65590
TEST=Turn on instant, switch to a search engine other than google and
  make sure you don't see any instant results.

Review URL: http://codereview.chromium.org/5599005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68514 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 25 insertions, 15 deletions

diff --git a/chrome/browser/instant/instant_controller.cc b/chrome/browser/instant/instant_controller.cc
index ebbd4b0..02872b4 100644
--- a/chrome/browser/instant/instant_controller.cc
+++ b/chrome/browser/instant/instant_controller.cc
@@ -146,12 +146,13 @@ void InstantController::Update(TabContentsWrapper* tab_contents,
     DestroyPreviewContents();
 
   const GURL& url = match.destination_url;
-
   tab_contents_ = tab_contents;
   commit_on_mouse_up_ = false;
   last_transition_type_ = match.transition;
+  const TemplateURL* template_url = NULL;
 
-  if (url.is_empty() || !url.is_valid() || !ShouldShowPreviewFor(match)) {
+  if (url.is_empty() || !url.is_valid() ||
+      !ShouldShowPreviewFor(match, &template_url)) {
     DestroyPreviewContents();
     return;
   }
@@ -162,7 +163,6 @@ void InstantController::Update(TabContentsWrapper* tab_contents,
   if (!is_active_)
     delegate_->PrepareForInstant();
 
-  const TemplateURL* template_url = GetTemplateURL(match);
   TemplateURLID template_url_id = template_url ? template_url->id() : 0;
   // Verbatim only makes sense if the search engines supports instant.
   bool real_verbatim = template_url_id ? verbatim : false;
@@ -450,7 +450,21 @@ void InstantController::UpdateLoader(const TemplateURL* template_url,
     delegate_->ShowInstant(new_loader->preview_contents());
 }
 
-bool InstantController::ShouldShowPreviewFor(const AutocompleteMatch& match) {
+bool InstantController::ShouldShowPreviewFor(const AutocompleteMatch& match,
+                                             const TemplateURL** template_url) {
+  const TemplateURL* t_url = GetTemplateURL(match);
+  if (t_url) {
+    if (!t_url->id() ||
+        !t_url->instant_url() ||
+        IsBlacklistedFromInstant(t_url->id()) ||
+        !t_url->instant_url()->SupportsReplacement()) {
+      // To avoid extra load on other search engines we only enable previews if
+      // they support the instant API.
+      return false;
+    }
+  }
+  *template_url = t_url;
+
   if (match.destination_url.SchemeIs(chrome::kJavaScriptScheme))
     return false;
 
@@ -492,13 +506,7 @@ const TemplateURL* InstantController::GetTemplateURL(
     TemplateURLModel* model = tab_contents_->profile()->GetTemplateURLModel();
     template_url = model ? model->GetDefaultSearchProvider() : NULL;
   }
-  if (template_url && template_url->id() &&
-      template_url->instant_url() &&
-      !IsBlacklistedFromInstant(template_url->id()) &&
-      template_url->instant_url()->SupportsReplacement()) {
-    return template_url;
-  }
-  return NULL;
+  return template_url;
 }
 
 // static
diff --git a/chrome/browser/instant/instant_controller.h b/chrome/browser/instant/instant_controller.h
index 09951da..912f1aa 100644
--- a/chrome/browser/instant/instant_controller.h
+++ b/chrome/browser/instant/instant_controller.h
@@ -192,8 +192,10 @@ class InstantController : public InstantLoaderDelegate {
                     bool verbatim,
                     string16* suggested_text);
 
-  // Returns true if we should show preview for |match|.
-  bool ShouldShowPreviewFor(const AutocompleteMatch& match);
+  // Returns true if a preview should be shown for |match|. If |match| has
+  // a TemplateURL that supports the instant API it is set in |template_url|.
+  bool ShouldShowPreviewFor(const AutocompleteMatch& match,
+                            const TemplateURL** template_url);
 
   // Marks the specified search engine id as not supporting instant.
   void BlacklistFromInstant(TemplateURLID id);
@@ -205,8 +207,8 @@ class InstantController : public InstantLoaderDelegate {
   // Clears the set of search engines blacklisted.
   void ClearBlacklist();
 
-  // Returns the TemplateURL to use for the specified AutocompleteMatch, or NULL
-  // if non TemplateURL should be used.
+  // Returns the TemplateURL to use for the specified AutocompleteMatch, or
+  // NULL if there is no TemplateURL for |match|.
   const TemplateURL* GetTemplateURL(const AutocompleteMatch& match);
 
   // If instant is enabled for the specified profile the type of instant is set