Add tests for navigation type classifications.

content/public/browser/navigation_type.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_NAVIGATION_TYPE_H_
 #define CONTENT_PUBLIC_BROWSER_NAVIGATION_TYPE_H_
 
 namespace content {
 
 // Indicates different types of navigations that can occur that we will handle
 // separately.
 enum NavigationType {
   // Unknown type.
   NAVIGATION_TYPE_UNKNOWN,
 
-  // A new page was navigated in the main frame.
+  // A new page was navigated to in the main frame. This covers all cases where
+  // the main frame navigated and a new navigation entry was created. This means
+  // cases like navigations to a hash on the same page are NEW_PAGE, not
+  // IN_PAGE. (Navigation entries created by subframe navigations are
+  // NEW_SUBFRAME.)
   NAVIGATION_TYPE_NEW_PAGE,
 
-  // Renavigating to an existing navigation entry. The entry is guaranteed to
-  // exist in the list, or else it would be a new page or IGNORE navigation.
+  // Renavigating to an existing navigation entry. This is the case for history
+  // navigation, reloads, and location.replace().
   NAVIGATION_TYPE_EXISTING_PAGE,
 
   // The same page has been reloaded as a result of the user requesting
   // navigation to that same page (like pressing Enter in the URL bar). This
   // is not the same as an in-page navigation because we'll actually have a
   // pending entry for the load, which is then meaningless.
   NAVIGATION_TYPE_SAME_PAGE,
 
-  // In page navigations are when the reference fragment changes. This will
-  // be in the main frame only (we won't even get notified of in-page
-  // subframe navigations). It may be for any page, not necessarily the last
-  // committed one (for example, whey going back to a page with a ref).
+  // The navigation was in the main frame, to a different navigation entry, but
+  // appearing to the user to be a navigation within the same page. This is the
+  // case for history.replaceState(), as well as back and forward across
+  // fragment entries and history.pushState() entries.
   NAVIGATION_TYPE_IN_PAGE,
 
   // A new subframe was manually navigated by the user. We will create a new
   // NavigationEntry so they can go back to the previous subframe content
   // using the back button.
   NAVIGATION_TYPE_NEW_SUBFRAME,
 
   // A subframe in the page was automatically loaded or navigated to such that
   // a new navigation entry should not be created. There are two cases:
   //  1. Stuff like iframes containing ads that the page loads automatically.
   //     The user doesn't want to see these, so we just update the existing
   //     navigation entry.
   //  2. Going back/forward to previous subframe navigations. We don't create
   //     a new entry here either, just update the last committed entry.
   // These two cases are actually pretty different, they just happen to
   // require almost the same code to handle.
   NAVIGATION_TYPE_AUTO_SUBFRAME,
 
   // Nothing happened. This happens when we get information about a page we
   // don't know anything about. It can also happen when an iframe in a popup
   // navigated to about:blank is navigated. Nothing needs to be done.
   NAVIGATION_TYPE_NAV_IGNORE,
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_TYPE_H_