Move instant support to SearchTabHelper. Fix InstantTab reset.

chrome/browser/ui/search/instant_page.h

Index: chrome/browser/ui/search/instant_page.h
diff --git a/chrome/browser/ui/search/instant_page.h b/chrome/browser/ui/search/instant_page.h
index 6bae2655ca53bbfffd6a6a4075cb571f7e0d283c..6930518665794214041acdaadd9a6908e90761af 100644
--- a/chrome/browser/ui/search/instant_page.h
+++ b/chrome/browser/ui/search/instant_page.h
@@ -10,6 +10,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/string16.h"
+#include "chrome/browser/ui/search/search_model_observer.h"
 #include "chrome/common/instant_types.h"
 #include "chrome/common/omnibox_focus_state.h"
 #include "content/public/browser/web_contents_observer.h"
@@ -29,7 +30,8 @@ class Rect;
 // Instant/Embedded Search API (http://dev.chromium.org/embeddedsearch).
 // InstantPage is not used directly but via one of its derived classes:
 // InstantOverlay, InstantNTP and InstantTab.
-class InstantPage : public content::WebContentsObserver {
+class InstantPage : public content::WebContentsObserver,
+                    public SearchModelObserver {
  public:
   // InstantPage calls its delegate in response to messages received from the
   // page. Each method is called with the |contents| corresponding to the page
@@ -216,6 +218,16 @@ class InstantPage : public content::WebContentsObserver {
       content::PageTransition transition_type,
       content::RenderViewHost* render_view_host) OVERRIDE;
 
+  // Overridden from SearchModelObserver:
+  virtual void ModelChanged(const SearchModel::State& old_state,
+                            const SearchModel::State& new_state) OVERRIDE;
+
+  // Helper to look up the SearchModel for this page.
+  SearchModel* GetSearchModel();
+
+  // Update the status of Instant support.
+  void SetSupportsInstant(bool supports_instant);
+
   void OnSetSuggestions(int page_id,
                         const std::vector<InstantSuggestion>& suggestions);
   void OnInstantSupportDetermined(int page_id, bool supports_instant);
@@ -233,6 +245,7 @@ class InstantPage : public content::WebContentsObserver {
 
   Delegate* const delegate_;
   const std::string instant_url_;
+  const bool extended_enabled_;
   bool supports_instant_;
 
   DISALLOW_COPY_AND_ASSIGN(InstantPage);