Switch to using the new Link Doctor API.

chrome/browser/ui/link_doctor_tab_observer.h

Index: chrome/browser/ui/link_doctor_tab_observer.h
===================================================================
--- chrome/browser/ui/link_doctor_tab_observer.h	(revision 248295)
+++ chrome/browser/ui/link_doctor_tab_observer.h	(working copy)
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
-#define CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
+#ifndef CHROME_BROWSER_UI_LINK_DOCTOR_TAB_OBSERVER_H_
+#define CHROME_BROWSER_UI_LINK_DOCTOR_TAB_OBSERVER_H_
 
 #include "base/prefs/pref_change_registrar.h"
 #include "content/public/browser/notification_observer.h"
@@ -17,19 +17,19 @@
 class PrefRegistrySyncable;
 }
 
-// Per-tab class to implement alternate error page functionality.
-class AlternateErrorPageTabObserver
+// Per-tab class to implement Link Doctor functionality.

[Peter Kasting, 2014/02/10 23:19:46]

I'm mildly concerned about using the phrase "link doctor" everywhere.

First, do we explain what that means anywhere?  If so we should probably cite
the relevant header file here; otherwise we should document on this class what
that actually means.  This existing one-line comment doesn't really tell us
anything the class name doesn't already.

Second, do we really want to use this phrase in general?  With the old code we'd
purposefully chosen "alternate error page" because it was both more descriptive
(for laymen) and more generic; LinkDoctor was kind of an internal Google name,
and could be changed, or we could modify Chrome to support other services or
whatever.

I'm not staunchly opposed to this name, I just want to make sure the above
factors have been considered.

[mmenke, 2014/02/10 23:29:02]

The "alternate error page" was a page served off of a Google server, in place of
a locally generated error page (See http://invalidurl/ vs http:/0.0.0.0:7/, with
"use a service to resolve navigation errors" enabled in chrome://settings).

This service is being discontinued.  Instead, we download a list of suggested
URLs in JSON format, wrap them with text from chrome, and replace the
suggestions of the current net error pages, so it's no longer really an
"alternate" error page, but rather a normal error page with alternate
suggestions.  Given that we're depending on very specific JSON parameters in the
request and response, I don't think it can even remotely be considered some sort
general error page service

I'll add some text documenting what the service is and does, and I'm certainly
not set on this name by any means, but I don't think "alternate error page" is
accurate any more.

[mmenke, 2014/02/10 23:40:35]

Maybe call it the NavigationCorrectionObserver, and referring to it in text and
some variables as the "navigation correction service"?  Using "service" in the
class names seems confusing.  That uses similar wording to the configuration
option, and gets away from using the Link Doctor name.

+class LinkDoctorTabObserver
     : public content::WebContentsObserver,
       public content::NotificationObserver,
-      public content::WebContentsUserData<AlternateErrorPageTabObserver> {
+      public content::WebContentsUserData<LinkDoctorTabObserver> {
  public:
-  virtual ~AlternateErrorPageTabObserver();
+  virtual ~LinkDoctorTabObserver();
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
  private:
-  explicit AlternateErrorPageTabObserver(content::WebContents* web_contents);
-  friend class content::WebContentsUserData<AlternateErrorPageTabObserver>;
+  explicit LinkDoctorTabObserver(content::WebContents* web_contents);
+  friend class content::WebContentsUserData<LinkDoctorTabObserver>;
 
   // content::WebContentsObserver overrides:
   virtual void RenderViewCreated(
@@ -42,20 +42,20 @@
 
   // Internal helpers ----------------------------------------------------------
 
-  // Returns the server that can provide alternate error pages.  If the returned
-  // URL is empty, the default error page built into WebKit will be used.
-  GURL GetAlternateErrorPageURL() const;
+  // Returns the URL for the Link Doctor FixURL service.  If the returned URL
+  // is empty, the default error pages will be used.
+  GURL GetLinkDoctorURL() const;
 
-  void OnAlternateErrorPagesEnabledChanged();
+  void OnLinkDoctorEnabledChanged();
 
-  // Send the alternate error page URL to the renderer.
-  void UpdateAlternateErrorPageURL(content::RenderViewHost* rvh);
+  // Updates the renderer's Link Doctor FixURL service configuration.
+  void UpdateLinkDoctorInfo(content::RenderViewHost* rvh);
 
   Profile* profile_;
   content::NotificationRegistrar registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
-  DISALLOW_COPY_AND_ASSIGN(AlternateErrorPageTabObserver);
+  DISALLOW_COPY_AND_ASSIGN(LinkDoctorTabObserver);
 };
 
-#endif  // CHROME_BROWSER_UI_ALTERNATE_ERROR_TAB_OBSERVER_H_
+#endif  // CHROME_BROWSER_UI_LINK_DOCTOR_TAB_OBSERVER_H_