Mojo cpp bindings: support Clone() for structs and arrays which don't contain handles.

mojo/public/cpp/bindings/array.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_ARRAY_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_ARRAY_H_
 
 #include <string.h>
 
 #include <algorithm>
@@ skipping 87 matching lines @@
 
   void Swap(Array* other) {
     std::swap(is_null_, other->is_null_);
     vec_.swap(other->vec_);
   }
   void Swap(std::vector<StorageType>* other) {
     is_null_ = false;
     vec_.swap(*other);
   }
 
+  // Please note that calling this method will fail compilation if the element
+  // type cannot be cloned (which usually means that it is a Mojo handle type or
+  // a type contains Mojo handles).
+  Array Clone() const {
+    Array result;
+    result.is_null_ = is_null_;
+    Traits::Clone(vec_, &result.vec_);
+    return result.Pass();
+  }
+
  private:
   typedef std::vector<StorageType> Array::*Testable;
 
  public:
   operator Testable() const { return is_null_ ? 0 : &Array::vec_; }
 
  private:
   void Take(Array* other) {
     reset();
     Swap(other);
@@ skipping 22 matching lines @@
       for (size_t i = 0; i < input.size(); ++i)
         result[i] = TypeConverter<E, T>::Convert(input[i]);
     }
     return result;
   }
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_ARRAY_H_