Add support for writing unit tests for Mojo-backed apps/extensions APIs.

This change adds the infrastructure for unit testing the JS parts of
apps and extensions APIs implemented on top of Mojo services. The test
environment provides a partial implementation of the JS test API
provided to browser tests. A TestServiceProvider implementation is
used to provide test implementations of the appropriate Mojo services to
the JS code.

BUG=389016

Review URL: https://codereview.chromium.org/399363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285792 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/extensions/renderer/module_system_test.cc b/extensions/renderer/module_system_test.cc
index 72f1dbb5..4f4675e 100644
--- a/extensions/renderer/module_system_test.cc
+++ b/extensions/renderer/module_system_test.cc
@@ -131,7 +131,7 @@
   context_.reset(new ScriptContext(context_holder_->context(),
                                    NULL,  // WebFrame
                                    NULL,  // Extension
-                                   Feature::UNSPECIFIED_CONTEXT));
+                                   Feature::BLESSED_EXTENSION_CONTEXT));
   context_->v8_context()->Enter();
   assert_natives_ = new AssertNatives(context_.get());