[Experimental] Supporting OOPIF printing

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 9675f6cba5a57a9a0aa996656ae24ebbbae40741..c7c1b37200a3b8c713e31331cd069fcaf767b99e 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -1567,6 +1567,7 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
                         OnSuppressFurtherDialogs)
     IPC_MESSAGE_HANDLER(FrameMsg_RunFileChooserResponse, OnFileChooserResponse)
     IPC_MESSAGE_HANDLER(FrameMsg_ClearFocusedElement, OnClearFocusedElement)
+    IPC_MESSAGE_HANDLER(FrameMsg_PrintFrame, OnPrintFrame)
 #if defined(OS_ANDROID)
     IPC_MESSAGE_HANDLER(FrameMsg_ActivateNearestFindResult,
                         OnActivateNearestFindResult)
@@ -5694,6 +5695,12 @@ void RenderFrameImpl::OnClearFocusedElement() {
     webview->clearFocusedElement();
 }
 
+void RenderFrameImpl::OnPrintFrame(const gfx::Rect& rect, int src_id) {
+  // Notify our observer to set up printing.
+  for (auto& observer : observers_)
+    observer.PrintFrame(rect, src_id);
+}
+
 #if defined(OS_ANDROID)
 void RenderFrameImpl::OnActivateNearestFindResult(int request_id,
                                                   float x,