Make test proxy Platform objects provide currentThread().

Source/core/animation/CompositorAnimationsTestHelper.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 124 matching lines @@
 
     class WebCompositorSupportMock : public WebCompositorSupport {
     public:
         MOCK_METHOD4(createAnimation, WebCompositorAnimation*(const WebCompositorAnimationCurve& curve, WebCompositorAnimation::TargetProperty target, int groupId, int animationId));
         MOCK_METHOD0(createFloatAnimationCurve, WebFloatAnimationCurve*());
     };
 
 private:
     class PlatformProxy : public Platform {
     public:
-        PlatformProxy(WebCompositorSupportMock** compositor) : m_compositor(compositor) { }
+        PlatformProxy(WebCompositorSupportMock** compositor) : m_platform(Platform::current()), m_compositor(compositor) { }
+
+        ~PlatformProxy()
+        {
+            blink::Platform::initialize(m_platform);
+        }
 
         virtual void cryptographicallyRandomValues(unsigned char* buffer, size_t length) { ASSERT_NOT_REACHED(); }
         const unsigned char* getTraceCategoryEnabledFlag(const char* categoryName) override
         {
             static const unsigned char tracingIsDisabled = 0;
             return &tracingIsDisabled;
         }
 
+        WebThread* currentThread() override
+        {
+            return m_platform->currentThread();
+        }
+
     private:
+        blink::Platform* m_platform; // Not owned.
         WebCompositorSupportMock** m_compositor;
         virtual WebCompositorSupport* compositorSupport() override { return *m_compositor; }
     };
 
     WebCompositorSupportMock* m_mockCompositor;
     PlatformProxy m_proxyPlatform;
 
 protected:
-    Platform* m_platform;
-
     virtual void SetUp()
     {
         m_mockCompositor = 0;
-        m_platform = Platform::current();
         Platform::initialize(&m_proxyPlatform);
     }
 
-    virtual void TearDown()
-    {
-        Platform::initialize(m_platform);
-    }
-
     void setCompositorForTesting(WebCompositorSupportMock& mock)
     {
         ASSERT(!m_mockCompositor);
         m_mockCompositor = &mock;
     }
 };
 
 }
 
 #endif