Extract InstallVerifier from ExtensionSystem.

chrome/browser/extensions/extension_system_impl.h

Index: chrome/browser/extensions/extension_system_impl.h
diff --git a/chrome/browser/extensions/extension_system_impl.h b/chrome/browser/extensions/extension_system_impl.h
index 78c4cf64ca3bf2702e78756a54b7fca1ead22323..fc05c7e5a6e41bac4dd60d106d72c5b7b3c0e1f4 100644
--- a/chrome/browser/extensions/extension_system_impl.h
+++ b/chrome/browser/extensions/extension_system_impl.h
@@ -16,6 +16,7 @@ namespace extensions {
 
 class ContentVerifier;
 class ExtensionSystemSharedFactory;
+class InstallVerifier;
 class NavigationObserver;
 class SharedUserScriptMaster;
 class StateStoreNotificationObserver;
@@ -46,7 +47,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
   LazyBackgroundTaskQueue* lazy_background_task_queue() override;  // shared
   InfoMap* info_map() override;                                    // shared
   EventRouter* event_router() override;                            // shared
-  InstallVerifier* install_verifier() override;
   QuotaService* quota_service() override;  // shared
 
   void RegisterExtensionWithRequestContexts(
@@ -90,7 +90,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
     InfoMap* info_map();
     LazyBackgroundTaskQueue* lazy_background_task_queue();
     EventRouter* event_router();
-    InstallVerifier* install_verifier();
     QuotaService* quota_service();
     const OneShotEvent& ready() const { return ready_; }
     ContentVerifier* content_verifier();
@@ -121,7 +120,6 @@ class ExtensionSystemImpl : public ExtensionSystem {
     scoped_ptr<ManagementPolicy> management_policy_;
     // extension_info_map_ needs to outlive process_manager_.
     scoped_refptr<InfoMap> extension_info_map_;
-    scoped_ptr<InstallVerifier> install_verifier_;
     scoped_ptr<QuotaService> quota_service_;
 
     // For verifying the contents of extensions read from disk.