Make test proxy Platform objects provide currentThread().

Source/core/fetch/CachingCorrectnessTest.cpp

Index: Source/core/fetch/CachingCorrectnessTest.cpp
diff --git a/Source/core/fetch/CachingCorrectnessTest.cpp b/Source/core/fetch/CachingCorrectnessTest.cpp
index b729004a7782da1ba3c50864f2a29f05119eb7d0..55793eb383c42d683054373f0c9ffdd1289c704f 100644
--- a/Source/core/fetch/CachingCorrectnessTest.cpp
+++ b/Source/core/fetch/CachingCorrectnessTest.cpp
@@ -124,13 +124,30 @@ private:
     // A simple platform that mocks out the clock, for cache freshness testing.
     class ProxyPlatform : public blink::Platform {
     public:
-        ProxyPlatform() : m_elapsedSeconds(0.) { }
+        ProxyPlatform()
+            : m_elapsedSeconds(0.)
+            , m_platform(Platform::current())
+        {
+        }
+
+        ~ProxyPlatform()
+        {
+            blink::Platform::initialize(m_platform);
+        }
 
         void advanceClock(double seconds)
         {
             m_elapsedSeconds += seconds;
         }
 
+        virtual WebThread* currentThread() override
+        {
+            if (m_platform)
+                return m_platform->currentThread();
+
+            return nullptr;
+        }
+
     private:
         // From blink::Platform:
         virtual double currentTime()
@@ -146,11 +163,12 @@ private:
         }
 
         double m_elapsedSeconds;
+
+        Platform* m_platform;
     };
 
     virtual void SetUp()
     {
-        m_savedPlatform = blink::Platform::current();
         blink::Platform::initialize(&m_proxyPlatform);
 
         // Save the global memory cache to restore it upon teardown.
@@ -165,11 +183,8 @@ private:
 
         // Yield the ownership of the global memory cache back.
         replaceMemoryCacheForTesting(m_globalMemoryCache.release());
-
-        blink::Platform::initialize(m_savedPlatform);
     }
 
-    blink::Platform* m_savedPlatform;
     ProxyPlatform m_proxyPlatform;
 
     OwnPtrWillBePersistent<MemoryCache> m_globalMemoryCache;