fileSystem() for the blink::Platform used in blink unit tests.

content/test/test_webkit_platform_support.h

Index: content/test/test_webkit_platform_support.h
diff --git a/content/test/test_webkit_platform_support.h b/content/test/test_webkit_platform_support.h
index 2bda542303e78f13474ec86fe9544cc531877cc8..0d12caffeb421b7a6d7bb52d495f92ebcd273f49 100644
--- a/content/test/test_webkit_platform_support.h
+++ b/content/test/test_webkit_platform_support.h
@@ -25,6 +25,10 @@ class WebLayerTreeView;
 }
 
 namespace content {
+class WebFileSystemImpl;
+}
+
+namespace content {
 
 // An implementation of WebKitPlatformSupport for tests.
 class TestWebKitPlatformSupport
@@ -36,6 +40,7 @@ class TestWebKitPlatformSupport
 
   virtual blink::WebBlobRegistry* blobRegistry();
   virtual blink::WebClipboard* clipboard();
+  virtual blink::WebFileSystem* fileSystem();
   virtual blink::WebFileUtilities* fileUtilities();
   virtual blink::WebIDBFactory* idbFactory();
   virtual blink::WebMimeRegistry* mimeRegistry();