Add test_runner hook to dump drag image.

content/shell/renderer/test_runner/web_test_proxy.h

Index: content/shell/renderer/test_runner/web_test_proxy.h
diff --git a/content/shell/renderer/test_runner/web_test_proxy.h b/content/shell/renderer/test_runner/web_test_proxy.h
index e06d572380da806ae55af35642d6e5d74f8d2f99..88dd814c2e0ef9a40ac24d1f828dadec119d5f32 100644
--- a/content/shell/renderer/test_runner/web_test_proxy.h
+++ b/content/shell/renderer/test_runner/web_test_proxy.h
@@ -13,6 +13,7 @@
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "content/shell/renderer/test_runner/web_task.h"
+#include "third_party/WebKit/public/platform/WebImage.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
 #include "third_party/WebKit/public/platform/WebScreenInfo.h"
 #include "third_party/WebKit/public/platform/WebURLError.h"
@@ -44,7 +45,6 @@ class WebDataSource;
 class WebDragData;
 class WebFileChooserCompletion;
 class WebFrame;
-class WebImage;
 class WebLocalFrame;
 class WebMIDIAccessor;
 class WebMIDIAccessorClient;
@@ -254,6 +254,8 @@ class WebTestProxyBase {
 
   WebTaskList task_list_;
 
+  blink::WebImage drag_image_;
+
   scoped_ptr<SpellCheckClient> spellcheck_;
   scoped_ptr<MockWebUserMediaClient> user_media_client_;