Move instant support to SearchTabHelper. Fix InstantTab reset.

chrome/browser/ui/search/search_model.h

 // Copyright (c) 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.
 
 #ifndef CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_
 #define CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_
 
 #include "base/basictypes.h"
 #include "base/observer_list.h"
 #include "chrome/common/search_types.h"
 
 class SearchModelObserver;
 
+// Represents whether a page supports Instant.
+enum InstantSupportState {
+  INSTANT_SUPPORT_NO,
+  INSTANT_SUPPORT_YES,
+  INSTANT_SUPPORT_UNKNOWN,
+};
+
 // An observable model for UI components that care about search model state
 // changes.
 class SearchModel {
  public:
   struct State {
-    State() : top_bars_visible(true) {}
+    State()
+        : top_bars_visible(true),
+          instant_support(INSTANT_SUPPORT_UNKNOWN) {}
 
     bool operator==(const State& rhs) const {
-      return mode == rhs.mode && top_bars_visible == rhs.top_bars_visible;
+      return mode == rhs.mode && top_bars_visible == rhs.top_bars_visible &&
+          instant_support == rhs.instant_support;
     }
 
     // The display mode of UI elements such as the toolbar, the tab strip, etc.
     SearchMode mode;
 
     // The visibility of top bars such as bookmark and info bars.
     bool top_bars_visible;
+
+    // Does the current page support Instant?
+    InstantSupportState instant_support;
   };
 
   SearchModel();
   ~SearchModel();
 
   // Returns true if visibility in top bars should be changed based on
   // |old_state| and |new_state|.
   static bool ShouldChangeTopBarsVisibility(const State& old_state,
                                             const State& new_state);
 
   // Change the state.  Change notifications are sent to observers.
   void SetState(const State& state);
 
   // Get the current state.
   const State& state() const { return state_; }
 
   // Change the mode.  Change notifications are sent to observers.
   void SetMode(const SearchMode& mode);
 
   // Get the active mode.
   const SearchMode& mode() const { return state_.mode; }
 
   // Set visibility of top bars.  Change notifications are sent to observers.
   void SetTopBarsVisible(bool visible);
 
   // Get the visibility of top bars.
   bool top_bars_visible() const { return state_.top_bars_visible; }
 
+  // Set whether the page supporst Instant.  Change notifications are sent to
+  // observers.
+  void SetSupportsInstant(bool supports_instant);
+
+  // Get whether the page supports Instant.
+  InstantSupportState instant_support() const {
+    return state_.instant_support;
+  }
+
   // Add and remove observers.
   void AddObserver(SearchModelObserver* observer);
   void RemoveObserver(SearchModelObserver* observer);
 
  private:
   // Current state of model.
   State state_;
 
   // Observers.
   ObserverList<SearchModelObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(SearchModel);
 };
 
 #endif  // CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_