TestingPlatformSupport: register Platform instance correctly

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index 8c569a75d7f6661186734e11b8fcaa46690a2bb3..9c96d16094cb6b9a272679109d467306f2018d89 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -139,7 +139,9 @@ class BLINK_PLATFORM_EXPORT Platform {
   static void shutdown();
   static Platform* current();
 
-  // Used to switch the current platform only for testing.
+  // Used to switch the current platform only for testing. Since this method
+  // calls virtual methods internally, you should not call with self instance
+  // inside a Platform subclass's constructor.

[haraken, 2017/01/12 11:21:01]

// you should not pass in a Platform object that is not fully instantiated

[Takashi Toyoshima, 2017/01/12 12:13:02]

Done.

   static void setCurrentPlatformForTesting(Platform*);
 
   // May return null.