Convert UMA interface to IDL.

ppapi/tests/test_uma.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PAPPI_TESTS_TEST_UMA_H_
 #define PAPPI_TESTS_TEST_UMA_H_
 
 #include <string>
 
+#include "ppapi/c/private/ppb_uma_private.h"
 #include "ppapi/tests/test_case.h"
 
-struct PPB_UMA_Private;
-
 class TestUMA : public TestCase {
  public:
   explicit TestUMA(TestingInstance* instance) : TestCase(instance) {}
 
   // TestCase implementation.
   virtual bool Init();
   virtual void RunTests(const std::string& filter);
 
  private:
   std::string TestCount();
   std::string TestTime();
   std::string TestEnum();
 
   // Used by the tests that access the C API directly.
   const PPB_UMA_Private* uma_interface_;
 };
 
 #endif  // PAPPI_TESTS_TEST_UMA_H_