Fix ZoomController crash on kiosk launching.

chrome/browser/ui/zoom/zoom_controller.cc

Index: chrome/browser/ui/zoom/zoom_controller.cc
diff --git a/chrome/browser/ui/zoom/zoom_controller.cc b/chrome/browser/ui/zoom/zoom_controller.cc
index 4925a147b4ed42146d20c5779e7a8db6e214c985..50fb694637c18442d72ce12516f2ff581e83706d 100644
--- a/chrome/browser/ui/zoom/zoom_controller.cc
+++ b/chrome/browser/ui/zoom/zoom_controller.cc
@@ -79,9 +79,10 @@ bool ZoomController::SetZoomLevel(double zoom_level) {
 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 ||
@@ -134,9 +135,6 @@ bool ZoomController::SetZoomLevelByExtension(
     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;