Mac Support for drag-and-drop tests that start dragging via mouse simulation.

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 8c17eef9be6970a9fd9b47198fb2d10594983947..b990057cd49719a509bd5b17be0d88e7d2b9afd8 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -43,6 +43,7 @@
 #include "content/public/common/url_constants.h"
 #include "ipc/ipc_listener.h"
 #include "third_party/WebKit/public/platform/WebDisplayMode.h"
+#include "third_party/WebKit/public/platform/WebDragOperation.h"
 #include "ui/base/ime/text_input_mode.h"
 #include "ui/base/ime/text_input_type.h"
 #include "ui/events/gesture_detection/gesture_provider_config_helper.h"
@@ -83,6 +84,7 @@ class SyntheticGestureController;
 class TimeoutMonitor;
 class TouchEmulator;
 class WebCursor;
+struct DropData;
 struct EditCommand;
 struct ResizeParams;
 struct ScreenInfo;
@@ -576,6 +578,11 @@ class CONTENT_EXPORT RenderWidgetHostImpl : public RenderWidgetHost,
     return weak_factory_.GetWeakPtr();
   }
 
+  using DragStartCallback =
+      base::Callback<bool(const DropData& drop_data,
+                          blink::WebDragOperationsMask drag_operations_mask)>;
+  static void RegisterDragStartCallbackForTesting(DragStartCallback callback);
+
  protected:
   // ---------------------------------------------------------------------------
   // The following method is overridden by RenderViewHost to send upwards to