[Experimental] Supporting OOPIF printing

content/public/renderer/render_frame_observer.h

Index: content/public/renderer/render_frame_observer.h
diff --git a/content/public/renderer/render_frame_observer.h b/content/public/renderer/render_frame_observer.h
index 7211fdcd334185658fccdb079a15da1fd66a60b1..d65674cd75ac04189d6244f8524039e56ab7ac45 100644
--- a/content/public/renderer/render_frame_observer.h
+++ b/content/public/renderer/render_frame_observer.h
@@ -16,6 +16,7 @@
 #include "third_party/WebKit/public/platform/WebLoadingBehaviorFlag.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "third_party/WebKit/public/web/WebMeaningfulLayout.h"
+#include "ui/gfx/geometry/rect.h"
 #include "v8/include/v8.h"
 
 namespace blink {
@@ -124,6 +125,8 @@ class CONTENT_EXPORT RenderFrameObserver : public IPC::Listener,
   // Called when script in the page calls window.print().
   virtual void ScriptedPrint(bool user_initiated) {}
 
+  virtual void PrintFrame(const gfx::Rect& rect, int src_id) {}
+
   // IPC::Listener implementation.
   bool OnMessageReceived(const IPC::Message& message) override;