Suppress NEW_NAVIGATION_ENTRY prerenderer failures for ORIGIN_OFFLINE

chrome/browser/prerender/prerender_contents.cc

Index: chrome/browser/prerender/prerender_contents.cc
diff --git a/chrome/browser/prerender/prerender_contents.cc b/chrome/browser/prerender/prerender_contents.cc
index aea147d28bf082ac2336cfc8edae770afc03b79b..991ca9df2a0aaeac6f0f44d03abdcc8db62b0f44 100644
--- a/chrome/browser/prerender/prerender_contents.cc
+++ b/chrome/browser/prerender/prerender_contents.cc
@@ -577,6 +577,10 @@ void PrerenderContents::DidFinishLoad(
 void PrerenderContents::DidNavigateMainFrame(
     const content::LoadCommittedDetails& details,
     const content::FrameNavigateParams& params) {
+  // Offline requests are not subject to navigation and use of history.

[pasko, 2017/01/26 12:09:39]

I'd prefer something more verbose as a comment, like:

  // Prevent ORIGIN_OFFLINE prerenders from being destroyed on location.href
  // change, since the history is never merged for offline prerenders. Also
  // avoid adding aliases as they may potentially mark other valid requests to
  // offline as duplicate.

[dougarnett, 2017/01/26 16:27:39]

Done.

+  if (origin() == ORIGIN_OFFLINE)
+    return;
+
   // If the prerender made a second navigation entry, abort the prerender. This
   // avoids having to correctly implement a complex history merging case (this
   // interacts with location.replace) and correctly synchronize with the