Make args() accessors const

mojo/application_manager/application_manager_unittest.cc

Index: mojo/application_manager/application_manager_unittest.cc
diff --git a/mojo/application_manager/application_manager_unittest.cc b/mojo/application_manager/application_manager_unittest.cc
index d33e5bec08114686f5dfcd949b0cbeb1d345ae2f..1800dce3dfb113480db7190f572ce495c47e1dd2 100644
--- a/mojo/application_manager/application_manager_unittest.cc
+++ b/mojo/application_manager/application_manager_unittest.cc
@@ -108,7 +108,7 @@ class TestApplicationLoader : public ApplicationLoader,
 
   void set_context(TestContext* context) { context_ = context; }
   int num_loads() const { return num_loads_; }
-  const std::vector<std::string>& GetArgs() { return test_app_->args(); }
+  const std::vector<std::string>& GetArgs() const { return test_app_->args(); }
 
  private:
   // ApplicationLoader implementation.