Only trigger navigation in distiller if in print preview

chrome/browser/ui/webui/print_preview/print_preview_distiller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/print_preview/print_preview_distiller.h"
 
 #include <stdint.h>
 #include <string>
 #include <utility>
 
@@ skipping 118 matching lines @@
       content::RenderFrameHost* render_frame_host) override {
     // When a new RenderFrame is created for a distilled rendering
     // WebContents, tell the new RenderFrame it's being used for
     // prerendering before any navigations occur.  Note that this is
     // always triggered before the first navigation, so there's no
     // need to send the message just after the WebContents is created.
     render_frame_host->Send(new PrerenderMsg_SetIsPrerendering(
         render_frame_host->GetRoutingID(), true));
   }
 
+  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
+                     const GURL& validated_url) override {
+    // Notify distiller that print preview is using it.
+    dom_distiller::RunIsolatedJavaScript(
+        web_contents()->GetMainFrame(),
+        "var isPrintPreviewDistiller = true;");
+  }
+
   void DoPrintPreview() {
     RenderViewHost* rvh = web_contents()->GetRenderViewHost();
     rvh->Send(new PrintMsg_InitiatePrintPreview(rvh->GetRoutingID(), false));
     rvh->Send(new PrintMsg_PrintPreview(rvh->GetRoutingID(), *settings_));
   }
 
   void DidGetRedirectForResourceRequest(
       content::RenderFrameHost* render_frame_host,
       const content::ResourceRedirectDetails& details) override {
     if (details.resource_type != content::RESOURCE_TYPE_MAIN_FRAME)
@@ skipping 127 matching lines @@
     WebContents* source_web_contents) {
   // TODO(ajwong): Remove the temporary map once prerendering is aware of
   // multiple session storage namespaces per tab.
   content::SessionStorageNamespaceMap session_storage_namespace_map;
   Profile* profile =
       Profile::FromBrowserContext(source_web_contents->GetBrowserContext());
   session_storage_namespace_map[std::string()] = session_storage_namespace;
   return WebContents::CreateWithSessionStorage(
       WebContents::CreateParams(profile), session_storage_namespace_map);
 }