Expand KeyedServiceProvider interface.

Add method GetHistoryServiceForBrowserStateIfExists that do not create the
HistoryService instance if it does not exists.

BUG=None

Review URL: https://codereview.chromium.org/1206303002

Cr-Commit-Position: refs/heads/master@{#336136}

3 files changed, 16 insertions, 0 deletions

diff --git a/ios/public/provider/chrome/browser/keyed_service_provider.h b/ios/public/provider/chrome/browser/keyed_service_provider.h
index c5c7862..5d054fd 100644
--- a/ios/public/provider/chrome/browser/keyed_service_provider.h
+++ b/ios/public/provider/chrome/browser/keyed_service_provider.h
@@ -107,6 +107,12 @@ class KeyedServiceProvider {
       ChromeBrowserState* browser_state,
       ServiceAccessType access_type) = 0;
 
+  // Returns an instance of history::HistoryService tied to |browser_state| if
+  // it exists, or null otherwise.
+  virtual history::HistoryService* GetHistoryServiceForBrowserStateIfExists(
+      ChromeBrowserState* browser_state,
+      ServiceAccessType access_type) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(KeyedServiceProvider);
 };
diff --git a/ios/public/test/test_keyed_service_provider.cc b/ios/public/test/test_keyed_service_provider.cc
index 016a5b3..1722bb8 100644
--- a/ios/public/test/test_keyed_service_provider.cc
+++ b/ios/public/test/test_keyed_service_provider.cc
@@ -145,4 +145,11 @@ TestKeyedServiceProvider::GetHistoryServiceForBrowserState(
   return nullptr;
 }
 
+history::HistoryService*
+TestKeyedServiceProvider::GetHistoryServiceForBrowserStateIfExists(
+    ChromeBrowserState* browser_state,
+    ServiceAccessType access_type) {
+  return nullptr;
+}
+
 }  // namespace ios
diff --git a/ios/public/test/test_keyed_service_provider.h b/ios/public/test/test_keyed_service_provider.h
index a3af1ab..e2e11f7 100644
--- a/ios/public/test/test_keyed_service_provider.h
+++ b/ios/public/test/test_keyed_service_provider.h
@@ -40,6 +40,9 @@ class TestKeyedServiceProvider : public KeyedServiceProvider {
   history::HistoryService* GetHistoryServiceForBrowserState(
       ChromeBrowserState* browser_state,
       ServiceAccessType access_type) override;
+  history::HistoryService* GetHistoryServiceForBrowserStateIfExists(
+      ChromeBrowserState* browser_state,
+      ServiceAccessType access_type) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestKeyedServiceProvider);