Move LazyBackgroundTaskQueueTest into extensions_unittests

extensions/browser/test_extensions_browser_client.h

Index: extensions/browser/test_extensions_browser_client.h
diff --git a/extensions/browser/test_extensions_browser_client.h b/extensions/browser/test_extensions_browser_client.h
index 5933e195a5a35934cc94f7f8d4b73d1b2a2a792d..7e77050abc224c8edf46728844dbd733d7b4dae5 100644
--- a/extensions/browser/test_extensions_browser_client.h
+++ b/extensions/browser/test_extensions_browser_client.h
@@ -22,6 +22,9 @@ class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
   void set_process_manager_delegate(ProcessManagerDelegate* delegate) {
     process_manager_delegate_ = delegate;
   }
+  void set_extension_system_factory(ExtensionSystemProvider* factory) {
+    extension_system_factory_ = factory;
+  }
 
   // Associates an incognito context with |main_context_|.
   void SetIncognitoContext(content::BrowserContext* incognito_context);
@@ -88,6 +91,9 @@ class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
   // Not owned, defaults to NULL.
   ProcessManagerDelegate* process_manager_delegate_;
 
+  // Not owned, defaults to NULL.
+  ExtensionSystemProvider* extension_system_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(TestExtensionsBrowserClient);
 };