Avoid duplicate functions/code in core/inspector.

third_party/WebKit/Source/core/inspector/IdentifiersFactory.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 36 matching lines @@
   return AddProcessIdPrefixTo(identifier);
 }
 
 // static
 String IdentifiersFactory::RequestId(unsigned long identifier) {
   return identifier ? AddProcessIdPrefixTo(identifier) : String();
 }
 
 // static
 String IdentifiersFactory::FrameId(LocalFrame* frame) {
+  if (!frame)
+    return String();
   return AddProcessIdPrefixTo(WeakIdentifierMap<LocalFrame>::Identifier(frame));
 }
 
 // static
 LocalFrame* IdentifiersFactory::FrameById(InspectedFrames* inspected_frames,
                                           const String& frame_id) {
   bool ok;
   int id = RemoveProcessIdPrefixFrom(frame_id, &ok);
   if (!ok)
     return nullptr;
@@ skipping 38 matching lines @@
   size_t dot_index = id.find('.');
 
   if (dot_index == kNotFound) {
     *ok = false;
     return 0;
   }
   return id.Substring(dot_index + 1).ToInt(ok);
 }
 
 }  // namespace blink