Only update a "not already visible" compact nav bar when we change host or scheme.

chrome/browser/ui/views/compact_nav/compact_location_bar_view_host.cc

 // Copyright (c) 2011 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/views/compact_nav/compact_location_bar_view_host.h"
 
 #if defined(TOOLKIT_USES_GTK)
 #include <gtk/gtk.h>
 #endif
 
@@ skipping 309 matching lines @@
                                           int to_index) {
   if (from_index == current_tab_model_index_) {
     UpdateOnTabChange(to_index, false);
     StartAutoHideTimer();
   }
 }
 
 void CompactLocationBarViewHost::TabChangedAt(TabContentsWrapper* contents,
                                               int index,
                                               TabChangeType change_type) {
-  if (IsCurrentTabIndex(index) && change_type ==
-      TabStripModelObserver::LOADING_ONLY) {
+  if (IsCurrentTabIndex(index) &&
+      change_type == TabStripModelObserver::LOADING_ONLY) {
+    TabContents* tab_contents = contents->tab_contents();
     bool was_not_visible = !IsVisible();
-    TabContents* tab_contents = contents->tab_contents();
+    if (was_not_visible) {
+      // Only show the compact navigation bar when we change hosts or scheme.
+      const GURL& new_url = tab_contents->GetURL();
+      GURL old_url = GetCompactLocationBarView()->location_bar_view()->
+          location_entry()->model()->PermanentURL();
+      if (old_url.has_host() && new_url.host() == old_url.host() &&

[SteveT, 2011/05/25 04:30:29]

Just checking your logic here. What is an example of an old URL with no host and
why should we always show the bar in this case?

My understanding of how Chrome (or all browsers in general) handles URLs is that
it always calculates the absolute URL from relative paths (ie-URLs with no
hosts, like "../a/b") and then stores the full URL in the location bar/tab
contents.

+          new_url.scheme() == old_url.scheme()) {
+        return;
+      }
+    }
     Update(tab_contents, false);
     if (was_not_visible) {
       if (tab_contents->is_loading()) {
         // Register to NavigationController LOAD_STOP so that we can autohide
         // when loading is done.
         if (!registrar_.IsRegistered(this, NotificationType::LOAD_STOP,
             Source<NavigationController>(&tab_contents->controller()))) {
           registrar_.Add(this, NotificationType::LOAD_STOP,
               Source<NavigationController>(&tab_contents->controller()));
         }
@@ skipping 164 matching lines @@
 bool CompactLocationBarViewHost::IsCurrentTabIndex(int index) {
   return current_tab_model_index_ == index;
 }
 
 bool CompactLocationBarViewHost::IsCurrentTab(TabContents* contents) {
   TabStripModel* tab_strip_model = browser_view()->browser()->tabstrip_model();
   return tab_strip_model->ContainsIndex(current_tab_model_index_) &&
       tab_strip_model->GetTabContentsAt(current_tab_model_index_)->
           tab_contents() == contents;
 }