jni: Forbid inappropriate JNI parameter conversions.

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 175 matching lines @@
   // local reference when it is done with it. Note that calling a Java method
   // is *not* a transfer of ownership and Release() should not be used.
   T Release() {
     return static_cast<T>(this->ReleaseInternal());
   }
 
  private:
   // This class is only good for use on the thread it was created on so
   // it's safe to cache the non-threadsafe JNIEnv* inside this object.
   JNIEnv* env_;
+
+  // Prevent ScopedJavaLocalRef(JNIEnv*, T obj) from being used to take
+  // ownership of a JavaParamRef's underlying object - parameters are not
+  // allowed to be deleted and so should not be owned by ScopedJavaLocalRef.
+  // TODO(torne): this can be removed once JavaParamRef no longer has an
+  // implicit conversion back to T.
+  ScopedJavaLocalRef(JNIEnv* env, const JavaParamRef<T>& other);
 };
 
 // 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() {}
@@ skipping 38 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_