Replace string16 with base::string16 in src/webkit

webkit/plugins/ppapi/mock_plugin_delegate.h

Index: webkit/plugins/ppapi/mock_plugin_delegate.h
diff --git a/webkit/plugins/ppapi/mock_plugin_delegate.h b/webkit/plugins/ppapi/mock_plugin_delegate.h
index b26ad9f7cbff882802717c64d0ee284121642993..4de2a6b308ab5e8c66983cf54a5a07b1c32703ea 100644
--- a/webkit/plugins/ppapi/mock_plugin_delegate.h
+++ b/webkit/plugins/ppapi/mock_plugin_delegate.h
@@ -24,11 +24,11 @@ class MockPluginDelegate : public PluginDelegate {
   virtual void PluginRequestedCancelComposition(PluginInstance* instance);
   virtual void PluginSelectionChanged(PluginInstance* instance);
   virtual void SimulateImeSetComposition(
-      const string16& text,
+      const base::string16& text,
       const std::vector<WebKit::WebCompositionUnderline>& underlines,
       int selection_start,
       int selection_end);
-  virtual void SimulateImeConfirmComposition(const string16& text);
+  virtual void SimulateImeConfirmComposition(const base::string16& text);
   virtual void PluginCrashed(PluginInstance* instance);
   virtual void InstanceCreated(PluginInstance* instance);
   virtual void InstanceDeleted(PluginInstance* instance);