[autofill] Adding new API to request an interactive autocomplete UI flow.

content/public/browser/web_contents_delegate.h

Index: content/public/browser/web_contents_delegate.h
diff --git a/content/public/browser/web_contents_delegate.h b/content/public/browser/web_contents_delegate.h
index aaed0b4f9296c0aeae23c80dac471ca7a9b78fc6..f482d9429beffb47751c85051c4163de65acd1f0 100644
--- a/content/public/browser/web_contents_delegate.h
+++ b/content/public/browser/web_contents_delegate.h
@@ -418,6 +418,9 @@ class CONTENT_EXPORT WebContentsDelegate {
       const MediaStreamRequest* request,
       const MediaResponseCallback& callback) {}
 
+  // Request to interactively fill out a form using autocomplete.
+  virtual void RequestAutocomplete(WebContents* web_contents) {}
+
 #if defined(OS_ANDROID)
   // Called when a compositing layer becomes available for this web contents
   // so the delegate can add it to the layer tree.