Prepare HistoryProvider for componentization

components/omnibox/autocomplete_provider_client.h

Index: components/omnibox/autocomplete_provider_client.h
diff --git a/components/omnibox/autocomplete_provider_client.h b/components/omnibox/autocomplete_provider_client.h
index 0cbdc07688f1192e44e9b2dea53551d2d98e8de8..ce217f00b93cb1e4908f099736ccfc7076a51743 100644
--- a/components/omnibox/autocomplete_provider_client.h
+++ b/components/omnibox/autocomplete_provider_client.h
@@ -13,7 +13,12 @@ struct AutocompleteMatch;
 class AutocompleteSchemeClassifier;
 class GURL;
 
+namespace bookmarks {
+class BookmarkModel;
+}
+
 namespace history {
+class HistoryService;
 class URLDatabase;
 }
 
@@ -44,6 +49,12 @@ class AutocompleteProviderClient {
   // Returns the scheme classifier.
   virtual const AutocompleteSchemeClassifier& SchemeClassifier() = 0;
 
+  // Returns the HistoryService.

[Peter Kasting, 2015/06/12 16:20:23]

The order of these functions seems totally random.  For example, this seems like
it is very similar to InMemoryDatabase(), and not at all similar to Classify(),
but the latter is closer than the former.

Maybe these should be grouped: getters for various services/objects, oracle
functions, other utilities.  Or some other form of grouping that makes sense? 
Anything that isn't so random-seeming.

[blundell, 2015/06/15 08:51:33]

Agreed. I'll send you a separate CL for this as the reordering would introduce a
bunch of churn in this CL.

+  virtual history::HistoryService* HistoryService() = 0;
+
+  // Returns the bookmarks:BookmarkModel
+  virtual bookmarks::BookmarkModel* BookmarkModel() = 0;
+
   // Given some string |text| that the user wants to use for navigation,
   // determines how it should be interpreted.
   virtual void Classify(