Remove calls to deprecated MessageLoop methods in blimp.

blimp/client/core/contents/blimp_contents_manager_unittest.cc

Index: blimp/client/core/contents/blimp_contents_manager_unittest.cc
diff --git a/blimp/client/core/contents/blimp_contents_manager_unittest.cc b/blimp/client/core/contents/blimp_contents_manager_unittest.cc
index a8fe2a5242f05ab9b850b982d4b67921b49ecba2..d2b48296193e8203761e7173a9759e69b1db7747 100644
--- a/blimp/client/core/contents/blimp_contents_manager_unittest.cc
+++ b/blimp/client/core/contents/blimp_contents_manager_unittest.cc
@@ -6,6 +6,7 @@
 
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "blimp/client/core/compositor/blimp_compositor_dependencies.h"
 #include "blimp/client/core/contents/blimp_contents_impl.h"
 #include "blimp/client/core/contents/ime_feature.h"
@@ -119,7 +120,7 @@ TEST_F(BlimpContentsManagerTest, GetDestroyedBlimpContents) {
   EXPECT_CALL(tab_control_feature, CloseTab(id)).Times(1);
   blimp_contents.reset();
 
-  loop.RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
   EXPECT_EQ(nullptr, blimp_contents_manager.GetBlimpContents(id));
 }