Make mojo::system::Core not own the PlatformSupport.

mojo/edk/system/core_test_base.h

Index: mojo/edk/system/core_test_base.h
diff --git a/mojo/edk/system/core_test_base.h b/mojo/edk/system/core_test_base.h
index c2b5ee2eede3da14b0e1f9b7e74d35d52f63841d..26b79251a6b0719db250314397b50a974b61b384 100644
--- a/mojo/edk/system/core_test_base.h
+++ b/mojo/edk/system/core_test_base.h
@@ -5,9 +5,9 @@
 #ifndef MOJO_EDK_SYSTEM_CORE_TEST_BASE_H_
 #define MOJO_EDK_SYSTEM_CORE_TEST_BASE_H_
 
-#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
+#include "mojo/edk/embedder/simple_platform_support.h"
 #include "mojo/public/c/system/types.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -38,6 +38,7 @@ class CoreTestBase : public testing::Test {
   Core* core() { return core_; }
 
  private:
+  embedder::SimplePlatformSupport platform_support_;
   Core* core_;
 
   DISALLOW_COPY_AND_ASSIGN(CoreTestBase);