DevTools: Implement undo, redo operations for the DOMStorage views.

Source/core/inspector/InspectorDOMStorageAgent.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2013 Samsung Electronics. 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.
@@ skipping 89 matching lines @@
     m_state->setBoolean(DOMStorageAgentState::domStorageAgentEnabled, true);
     m_instrumentingAgents->setInspectorDOMStorageAgent(this);
 }
 
 void InspectorDOMStorageAgent::disable(ErrorString*)
 {
     m_instrumentingAgents->setInspectorDOMStorageAgent(0);
     m_state->setBoolean(DOMStorageAgentState::domStorageAgentEnabled, false);
 }
 
+void InspectorDOMStorageAgent::getValue(ErrorString* errorString, const RefPtr<JSONObject>& storageId, const String& key, TypeBuilder::OptOutput<WTF::String>* value)
+{
+    Frame* frame;
+    OwnPtr<StorageArea> storageArea = findStorageArea(errorString, storageId, frame);
+    if (!storageArea)
+        return;
+
+    TrackExceptionState es;
+    bool keyPresent = storageArea->contains(key, es, frame);
+    if (hadException(es, errorString) || !keyPresent)
+        return;
+
+    *value = storageArea->getItem(key, es, frame);
+    hadException(es, errorString);
+}
+
 void InspectorDOMStorageAgent::getDOMStorageItems(ErrorString* errorString, const RefPtr<JSONObject>& storageId, RefPtr<TypeBuilder::Array<TypeBuilder::Array<String> > >& items)
 {
     Frame* frame;
     OwnPtr<StorageArea> storageArea = findStorageArea(errorString, storageId, frame);
     if (!storageArea)
         return;
 
     RefPtr<TypeBuilder::Array<TypeBuilder::Array<String> > > storageItems = TypeBuilder::Array<TypeBuilder::Array<String> >::create();
 
     TrackExceptionState es;
@@ skipping 104 matching lines @@
     }
     targetFrame = frame;
 
     if (isLocalStorage)
         return StorageNamespace::localStorageArea(frame->document()->securityOrigin());
     return m_pageAgent->page()->sessionStorage()->storageArea(frame->document()->securityOrigin());
 }
 
 } // namespace WebCore