Fix devtools unable to start a shared workers.

chrome/browser/search/iframe_source.cc

 // Copyright 2013 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/search/iframe_source.h"
 
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/search/instant_io_context.h"
@@ skipping 34 matching lines @@
       ServesPath(path);
 }
 
 bool IframeSource::ShouldDenyXFrameOptions() const {
   return false;
 }
 
 bool IframeSource::GetOrigin(
     const content::ResourceRequestInfo::WebContentsGetter& wc_getter,
     std::string* origin) const {
+  if (wc_getter.is_null())
+    return false;
   content::WebContents* contents = wc_getter.Run();
+  if (!contents)
+    return false;
   const content::NavigationEntry* entry =
       contents->GetController().GetVisibleEntry();
   if (entry == NULL)
     return false;
 
   *origin = entry->GetURL().GetOrigin().spec();
   // Origin should not include a trailing slash. That is part of the path.
   base::TrimString(*origin, "/", origin);
   return true;
 }
@@ skipping 15 matching lines @@
     callback.Run(NULL);
     return;
   }
 
   base::StringPiece template_js =
       ResourceBundle::GetSharedInstance().GetRawDataResource(resource_id);
   std::string response(template_js.as_string());
   base::ReplaceFirstSubstringAfterOffset(&response, 0, "{{ORIGIN}}", origin);
   callback.Run(base::RefCountedString::TakeString(&response));
 }