Fix ZoomController crash on kiosk launching.

chrome/browser/ui/zoom/zoom_controller.cc

 // 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.
 
 #include "chrome/browser/ui/zoom/zoom_controller.h"
 
 #include "chrome/browser/ui/sad_tab.h"
 #include "chrome/browser/ui/zoom/zoom_event_manager.h"
 #include "chrome/browser/ui/zoom/zoom_observer.h"
 #include "content/public/browser/host_zoom_map.h"
@@ skipping 61 matching lines @@
 }
 
 bool ZoomController::SetZoomLevel(double zoom_level) {
   // An extension did not initiate this zoom change.
   return SetZoomLevelByExtension(zoom_level, NULL);
 }
 
 bool ZoomController::SetZoomLevelByExtension(
     double zoom_level,
     const scoped_refptr<const extensions::Extension>& extension) {
+  content::NavigationEntry* entry =
+      web_contents()->GetController().GetLastCommittedEntry();
   bool is_normal_page =
-      web_contents()->GetController().GetLastCommittedEntry()->GetPageType() ==
-      content::PAGE_TYPE_NORMAL;
+      entry && entry->GetPageType() == content::PAGE_TYPE_NORMAL;

[wjmaclean, 2014/09/26 21:05:44]

If there's no committed entry, what are we zooming?

It seems like the proper thing to do here would be to exit without applying
zoom. Or is there something about kiosk mode that allows it to display valid
content without a committed entry? (In which case, what value of "host" is being
passed to the HostZoomMap?)

[xiyuan, 2014/09/26 21:39:37]

If there is no committed entry, |is_normal_page| would false and we bail out in
line 91, right?

[wjmaclean, 2014/09/26 23:48:39]

Sorry ... I realized shortly after I left the office that I ha read that line
wrong.

   // Cannot zoom in disabled mode. Also, don't allow changing zoom level on
   // a crashed tab, an error page or an interstitial page.
   if (zoom_mode_ == ZOOM_MODE_DISABLED ||
       !web_contents()->GetRenderViewHost()->IsRenderViewLive() ||
       !is_normal_page)
     return false;
 
   // Store extension data so that |extension| can be attributed when the zoom
   // change completes. We expect that by the time this function returns that
   // any observers that require this information will have requested it.
@@ skipping 32 matching lines @@
                                              zoom_level,
                                              zoom_mode_,
                                              false /* can_show_bubble */));
   int render_process_id = web_contents()->GetRenderProcessHost()->GetID();
   int render_view_id = web_contents()->GetRenderViewHost()->GetRoutingID();
   if (zoom_mode_ == ZOOM_MODE_ISOLATED ||
       zoom_map->UsesTemporaryZoomLevel(render_process_id, render_view_id)) {
     zoom_map->SetTemporaryZoomLevel(
         render_process_id, render_view_id, zoom_level);
   } else {
-    content::NavigationEntry* entry =
-        web_contents()->GetController().GetLastCommittedEntry();
-
     if (!entry) {
       last_extension_ = NULL;
       return false;
     }
     std::string host = net::GetHostOrSpecFromURL(entry->GetURL());
     zoom_map->SetZoomLevelForHost(host, zoom_level);
   }
 
   DCHECK(!event_data_);
   last_extension_ = NULL;
@@ skipping 141 matching lines @@
   } else {
     // TODO(wjmaclean) Should we consider having HostZoomMap send both old and
     // new zoom levels here?
     double zoom_level = GetZoomLevel();
     ZoomChangedEventData zoom_change_data(
         web_contents(), zoom_level, zoom_level, zoom_mode_, can_show_bubble);
     FOR_EACH_OBSERVER(
         ZoomObserver, observers_, OnZoomChanged(zoom_change_data));
   }
 }