Detach the dependency from host_content_settings_map to extension.

chrome/browser/content_settings/content_settings_mock_provider.cc

Index: chrome/browser/content_settings/content_settings_mock_provider.cc
diff --git a/chrome/browser/content_settings/content_settings_mock_provider.cc b/chrome/browser/content_settings/content_settings_mock_provider.cc
index ab7c4d910bf05f164319d77698fe4af5817053bc..8ccaa3b3bf7dbe24927b22b2521b4cf954e1aaf6 100644
--- a/chrome/browser/content_settings/content_settings_mock_provider.cc
+++ b/chrome/browser/content_settings/content_settings_mock_provider.cc
@@ -43,4 +43,12 @@ void MockProvider::ShutdownOnUIThread() {
   RemoveAllObservers();
 }
 
+std::string MockProvider::GetProviderName() const {
+  return "mock";
+}
+
+SettingSource MockProvider::GetSettingSource() const {
+  return SETTING_SOURCE_NONE;
+}
+
 }  // namespace content_settings