Move instant support to SearchTabHelper. Fix InstantTab reset.

chrome/browser/ui/search/search_tab_helper.h

Index: chrome/browser/ui/search/search_tab_helper.h
diff --git a/chrome/browser/ui/search/search_tab_helper.h b/chrome/browser/ui/search/search_tab_helper.h
index 3f6eb8922cb871f626795117ea09ec229c007122..6c0c87de33f175057ffd86d92afcc47217d49a55 100644
--- a/chrome/browser/ui/search/search_tab_helper.h
+++ b/chrome/browser/ui/search/search_tab_helper.h
@@ -51,15 +51,27 @@ class SearchTabHelper : public content::NotificationObserver,
 
   // Overridden from contents::WebContentsObserver:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+  virtual void DidFinishLoad(
+      int64 frame_id,
+      const GURL& validated_url,
+      bool is_main_frame,
+      content::RenderViewHost* render_view_host) OVERRIDE;
 
   // Sets the mode of the model based on the current URL of web_contents().
   void UpdateMode();
 
+  // Send an IPC to web_contents() to attempt to discover whether it supports
+  // instant.
+  void DetermineIfPageSupportsInstant();
+
   // Handlers for SearchBox API to show and hide top bars (bookmark and info
   // bars).
   void OnSearchBoxShowBars(int page_id);
   void OnSearchBoxHideBars(int page_id);
 
+  // Handler for when Instant support has been determined.
+  void OnInstantSupportDetermined(int page_id, bool supports_instant);
+
   const bool is_search_enabled_;
 
   // Tracks the last value passed to OmniboxEditModelChanged().