Renderer-side changes for NoState Prefetch

chrome/renderer/prerender/prerender_helper.h

Index: chrome/renderer/prerender/prerender_helper.h
diff --git a/chrome/renderer/prerender/prerender_helper.h b/chrome/renderer/prerender/prerender_helper.h
index 93bda9533cd420bff43b820de1c59381dcc20855..abc047d54429df6f687645a8c405b697a8c4df37 100644
--- a/chrome/renderer/prerender/prerender_helper.h
+++ b/chrome/renderer/prerender/prerender_helper.h
@@ -20,12 +20,21 @@ class PrerenderHelper
     : public content::RenderFrameObserver,
       public content::RenderFrameObserverTracker<PrerenderHelper> {
  public:
-  explicit PrerenderHelper(content::RenderFrame* render_frame);
+  PrerenderHelper(content::RenderFrame* render_frame,
+                  PrerenderMode prerender_mode);
+
+  // Must be called on a sub-frame. Inherits the prerender mode from the main
+  // frame.
+  explicit PrerenderHelper(content::RenderFrame* sub_frame);
+
   ~PrerenderHelper() override;
 
   // Returns true if |render_view| is currently prerendering.
   static bool IsPrerendering(const content::RenderFrame* render_frame);
 
+  static PrerenderMode GetPrerenderMode(
+      const content::RenderFrame* render_frame);
+
  private:
   // RenderFrameObserver implementation.
   bool OnMessageReceived(const IPC::Message& message) override;
@@ -33,6 +42,8 @@ class PrerenderHelper
 
   void OnSetIsPrerendering(PrerenderMode mode);
 
+  PrerenderMode prerender_mode_;
+
   DISALLOW_COPY_AND_ASSIGN(PrerenderHelper);
 };