PlzNavigate: send searchable form data to the browser side on form submission.

content/public/browser/navigation_handle.h

Index: content/public/browser/navigation_handle.h
diff --git a/content/public/browser/navigation_handle.h b/content/public/browser/navigation_handle.h
index b6ae5c7d0bdf999e8ea87b749888a5a40149e608..f2506c82dce30a5df29d0599180cd8268f09ae2a 100644
--- a/content/public/browser/navigation_handle.h
+++ b/content/public/browser/navigation_handle.h
@@ -94,6 +94,11 @@ class CONTENT_EXPORT NavigationHandle {
   // Whether or not the navigation was started within a context menu.
   virtual bool WasStartedFromContextMenu() const = 0;
 
+  // Returns the URL and encoding of an INPUT field that corresponds to a
+  // searchable form request.
+  virtual const GURL& GetSearchableFormURL() = 0;
+  virtual const std::string& GetSearchableFormEncoding() = 0;
+
   // Parameters available at network request start time ------------------------
   //
   // The following parameters are only available when the network request is