Centralize logic around Instant modes.

chrome/browser/autocomplete/search_provider.h

Index: chrome/browser/autocomplete/search_provider.h
diff --git a/chrome/browser/autocomplete/search_provider.h b/chrome/browser/autocomplete/search_provider.h
index 50631579c5f06660607687e6e643e86361431ce1..63b9bfab1ebe07a61e6dce24eabcfdd0cab3718e 100644
--- a/chrome/browser/autocomplete/search_provider.h
+++ b/chrome/browser/autocomplete/search_provider.h
@@ -59,6 +59,11 @@ class SearchProvider : public AutocompleteProvider,
   }
 #endif
 
+  // See comments for |instant_suggest_enabled_| below.
+  void set_instant_suggest_enabled(bool value) {
+    instant_suggest_enabled_ = value;
+  }
+
   // Marks the instant query as done. If |input_text| is non-empty this changes
   // the 'search what you typed' results text to |input_text| + |suggest_text|.
   // |input_text| is the text the user input into the edit. |input_text| differs
@@ -378,6 +383,9 @@ class SearchProvider : public AutocompleteProvider,
   // The |suggest_text| parameter passed to FinalizeInstantQuery.
   string16 default_provider_suggest_text_;
 
+  // True if Instant will autocomplete its suggestion into the omnibox.
+  bool instant_suggest_enabled_;
+
   DISALLOW_COPY_AND_ASSIGN(SearchProvider);
 };