Make BrowsingDataHandler observe WebHistoryService deletions

components/history/core/browser/web_history_service.h

Index: components/history/core/browser/web_history_service.h
diff --git a/components/history/core/browser/web_history_service.h b/components/history/core/browser/web_history_service.h
index 0b6c08bdc86839c3ef68300382d6a3bcb7c1ac5a..d5681a8d0f5db7dd9cab9d7e3091fd8d0704e021 100644
--- a/components/history/core/browser/web_history_service.h
+++ b/components/history/core/browser/web_history_service.h
@@ -14,6 +14,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/keyed_service/core/keyed_service.h"
 
@@ -34,6 +35,8 @@ class SigninManagerBase;
 
 namespace history {
 
+class WebHistoryServiceObserver;
+
 // Provides an API for querying Google servers for a signed-in user's
 // synced history visits. It is roughly analogous to HistoryService, and
 // supports a similar API.
@@ -95,6 +98,9 @@ class WebHistoryService : public KeyedService {
       const scoped_refptr<net::URLRequestContextGetter>& request_context);
   ~WebHistoryService() override;
 
+  void AddObserver(WebHistoryServiceObserver* observer);
+  void RemoveObserver(WebHistoryServiceObserver* observer);
+
   // Searches synced history for visits matching |text_query|. The timeframe to
   // search, along with other options, is specified in |options|. If
   // |text_query| is empty, all visits in the timeframe will be returned.
@@ -219,6 +225,9 @@ class WebHistoryService : public KeyedService {
   // complete by profile shutdown.
   std::set<Request*> pending_other_forms_of_browsing_history_requests_;
 
+  // Observers.
+  base::ObserverList<WebHistoryServiceObserver, true> observer_list_;
+
   base::WeakPtrFactory<WebHistoryService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebHistoryService);