Don't assume WebContents has a LastCommittedEntry when setting zoom.

content/browser/host_zoom_map_impl.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 "content/browser/host_zoom_map_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/strings/string_piece.h"
@@ skipping 224 matching lines @@
                                       net::GetHostOrSpecFromURL(url));
 }
 
 void HostZoomMapImpl::SetZoomLevelForWebContents(
     const WebContentsImpl& web_contents_impl,
     double level) {
   int render_process_id = web_contents_impl.GetRenderProcessHost()->GetID();
   int render_view_id = web_contents_impl.GetRenderViewHost()->GetRoutingID();
   if (UsesTemporaryZoomLevel(render_process_id, render_view_id)) {
     SetTemporaryZoomLevel(render_process_id, render_view_id, level);
   } else {

[Peter Kasting, 2014/06/09 18:17:57]

Tiny nit: For parallel structure with the function above, you might want to use
an early-return instead of this "else".  Up to you.

     // Get the url from the navigation controller directly, as calling
     // WebContentsImpl::GetLastCommittedURL() may give us a virtual url that
     // is different than what the render view is using. If the two don't match,
     // the attempt to set the zoom will fail.
     GURL url;
     NavigationEntry* entry =
         web_contents_impl.GetController().GetLastCommittedEntry();
-    DCHECK(entry);
-    url = entry->GetURL();
-    SetZoomLevelForHost(net::GetHostOrSpecFromURL(url), level);
+    if (entry) {

[Peter Kasting, 2014/06/09 18:17:57]

Nit: Add a comment about why this can be NULL.  Ideally, the comments both here
and above actually give the reader some detail about the codepath that leads to
this, rather than just saying something like "it's possible there is no entry
yet".

+      url = entry->GetURL();

[wjmaclean, 2014/06/09 17:35:59]

Actually, this should be 

GURL url = ...

No need to declare it outside the if()

+      SetZoomLevelForHost(net::GetHostOrSpecFromURL(url), level);
+    }
   }
 }
 
 void HostZoomMapImpl::SetZoomLevelForView(int render_process_id,
                                           int render_view_id,
                                           double level,
                                           const std::string& host) {
   if (UsesTemporaryZoomLevel(render_process_id, render_view_id))
     SetTemporaryZoomLevel(render_process_id, render_view_id, level);
   else
@@ skipping 118 matching lines @@
       zoom_level(0.0) {
 }
 
 bool HostZoomMapImpl::TemporaryZoomLevel::operator==(
     const TemporaryZoomLevel& other) const {
   return other.render_process_id == render_process_id &&
          other.render_view_id == render_view_id;
 }
 
 }  // namespace content