Move LazyBackgroundTaskQueueTest into extensions_unittests

Previously it ran as part of Chrome's unit_tests. This requires factoring out
the usage of TestingProfile and swapping in a MockExtensionSystem.

BUG=397164
TEST=extensions_unittests

Review URL: https://codereview.chromium.org/428953003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287267 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/extensions/browser/extensions_test.h b/extensions/browser/extensions_test.h
index ed16fe9..a8ab790c 100644
--- a/extensions/browser/extensions_test.h
+++ b/extensions/browser/extensions_test.h
@@ -5,6 +5,7 @@
 #ifndef EXTENSIONS_BROWSER_EXTENSIONS_TEST_H_
 #define EXTENSIONS_BROWSER_EXTENSIONS_TEST_H_
 
+#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -38,6 +39,10 @@
     return extensions_browser_client_.get();
   }
 
+  // testing::Test overrides:
+  virtual void SetUp() OVERRIDE;
+  virtual void TearDown() OVERRIDE;
+
  private:
   scoped_ptr<content::ContentClient> content_client_;
   scoped_ptr<content::ContentBrowserClient> content_browser_client_;