Verify all files in the request body are accessible by the renderer process.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index faa65b92808c66e4b56b274bcc22351c8bbd9fde..eaefe85478eaa657f51badbd53267838dd1187bf 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -955,6 +955,10 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // Called by |beforeunload_timeout_| when the beforeunload timeout fires.
   void BeforeUnloadTimeout();
 
+  // Ensures that the upload parameters sent by the renderer process are

[ncarter (slow), 2017/05/24 20:06:19]

"Ensures that" -> "Returns true if".

+  // valid and any files specified are allowed for access.
+  bool ValidateUploadParams(const CommonNavigationParams& common_params);
+
   // For now, RenderFrameHosts indirectly keep RenderViewHosts alive via a
   // refcount that calls Shutdown when it reaches zero.  This allows each
   // RenderFrameHostManager to just care about RenderFrameHosts, while ensuring