Move instant support to SearchTabHelper.

chrome/browser/ui/search/search_model.cc

 // 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.
 
 #include "chrome/browser/ui/search/search_model.h"
 
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/ui/search/search_model_observer.h"
 
+SearchModel::State::State()
+    : top_bars_visible(true),
+      instant_support(INSTANT_SUPPORT_UNKNOWN) {
+}
+
+SearchModel::State::State(const SearchMode& mode,
+                          bool top_bars_visible,
+                          InstantSupportState instant_support)
+    : mode(mode),
+      top_bars_visible(top_bars_visible),
+      instant_support(instant_support) {
+}
+
+bool SearchModel::State::operator==(const State& rhs) const {
+  return mode == rhs.mode && top_bars_visible == rhs.top_bars_visible &&
+      instant_support == rhs.instant_support;
+}
+
 SearchModel::SearchModel() {
 }
 
 SearchModel::~SearchModel() {
 }
 
 // static.
 bool SearchModel::ShouldChangeTopBarsVisibility(const State& old_state,
                                                 const State& new_state) {
   // If mode has changed, only change top bars visibility if new mode is not
@@ skipping 50 matching lines @@
   if (state_.top_bars_visible == visible)
     return;
 
   const State old_state = state_;
   state_.top_bars_visible = visible;
 
   FOR_EACH_OBSERVER(SearchModelObserver, observers_,
                     ModelChanged(old_state, state_));
 }
 
+void SearchModel::SetSupportsInstant(bool supports_instant) {

[samarth, 2013/05/10 01:32:38]

Can we follow Jered's lead in InstantPage and add some unit tests here as well? 
Some of the logic here is non trivial.

[kmadhusu, 2013/05/13 17:13:24]

Done.

+  DCHECK(chrome::IsInstantExtendedAPIEnabled())
+      << "Please do not try to set the SearchModel mode without first "
+      << "checking if Search is enabled.";
+
+  InstantSupportState new_instant_support = supports_instant ?
+      INSTANT_SUPPORT_YES : INSTANT_SUPPORT_NO;
+
+  if (state_.instant_support == new_instant_support)
+    return;
+
+  const State old_state = state_;
+  state_.instant_support = new_instant_support;
+
+  FOR_EACH_OBSERVER(SearchModelObserver, observers_,
+                    ModelChanged(old_state, state_));
+}
+
 void SearchModel::AddObserver(SearchModelObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void SearchModel::RemoveObserver(SearchModelObserver* observer) {
   observers_.RemoveObserver(observer);
 }