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 e7c587d52ed196311a3267bf389f6965f65adae1..1d1de6edf081f4350b267c83475789c280c5a538 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -961,6 +961,10 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // to |url|.
   void SetLastCommittedSiteUrl(const GURL& url);
 
+  // Ensures that the upload parameters sent by the renderer process are
+  // 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