Give ScopedJavaGlobalRef copy and assignment constructors

base/android/scoped_java_ref.h

 // Copyright (c) 2012 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 BASE_ANDROID_SCOPED_JAVA_REF_H_
 #define BASE_ANDROID_SCOPED_JAVA_REF_H_
 
 #include <jni.h>
 #include <stddef.h>
 
@@ skipping 209 matching lines @@
 
 // Holds a global reference to a Java object. The global reference is scoped
 // to the lifetime of this object. This class does not hold onto any JNIEnv*
 // passed to it, hence it is safe to use across threads (within the constraints
 // imposed by the underlying Java object that it references).
 template<typename T>
 class ScopedJavaGlobalRef : public JavaRef<T> {
  public:
   ScopedJavaGlobalRef() {}
 
-  explicit ScopedJavaGlobalRef(const ScopedJavaGlobalRef<T>& other) {
+  ScopedJavaGlobalRef(const ScopedJavaGlobalRef<T>& other) {
     this->Reset(other);
   }
 
   ScopedJavaGlobalRef(JNIEnv* env, T obj) { this->Reset(env, obj); }
 
   template<typename U>
   explicit ScopedJavaGlobalRef(const U& other) {
     this->Reset(other);
   }
 
   ~ScopedJavaGlobalRef() {
     this->Reset();
   }
 
+  // Overloaded assignment operator defined for consistency with the implicit
+  // copy constructor.
+  void operator=(const ScopedJavaGlobalRef<T>& other) {
+    this->Reset(other);
+  }
+
   void Reset() {
     this->ResetGlobalRef();
   }
 
   template<typename U>
   void Reset(const U& other) {
     this->Reset(NULL, other.obj());
   }
 
   template<typename U>
@@ skipping 13 matching lines @@
   // is *not* a transfer of ownership and Release() should not be used.
   T Release() {
     return static_cast<T>(this->ReleaseInternal());
   }
 };
 
 }  // namespace android
 }  // namespace base
 
 #endif  // BASE_ANDROID_SCOPED_JAVA_REF_H_