Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/java/src/main/java/com/google/protobuf/Extension.java

Index: third_party/protobuf/java/src/main/java/com/google/protobuf/Extension.java
diff --git a/third_party/protobuf/java/src/main/java/com/google/protobuf/Extension.java b/third_party/protobuf/java/src/main/java/com/google/protobuf/Extension.java
deleted file mode 100644
index 68d29f33d47b43ffaa1253903a5e12b1c3bb6f41..0000000000000000000000000000000000000000
--- a/third_party/protobuf/java/src/main/java/com/google/protobuf/Extension.java
+++ /dev/null
@@ -1,85 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-package com.google.protobuf;
-
-/**
- * Interface that generated extensions implement.
- *
- * @author liujisi@google.com (Jisi Liu)
- */
-public abstract class Extension<ContainingType extends MessageLite, Type>
-    extends ExtensionLite<ContainingType, Type> {
-
-  /** Returns the descriptor of the extension. */
-  public abstract Descriptors.FieldDescriptor getDescriptor();
-
-  /** Returns whether or not this extension is a Lite Extension. */
-  final boolean isLite() {
-    return false;
-  }
-
-  // All the methods below are extension implementation details.
-
-  /**
-   * The API type that the extension is used for.
-   */
-  protected enum ExtensionType {
-    IMMUTABLE,
-    MUTABLE,
-    PROTO1,
-  }
-
-  protected ExtensionType getExtensionType() {
-    // TODO(liujisi): make this abstract after we fix proto1.
-    return ExtensionType.IMMUTABLE;
-  }
-
-  /**
-   * Type of a message extension.
-   */
-  public enum MessageType {
-    PROTO1,
-    PROTO2,
-  }
-  
-  /**
-   * If the extension is a message extension (i.e., getLiteType() == MESSAGE),
-   * returns the type of the message, otherwise undefined.
-   */
-  public MessageType getMessageType() {
-    return MessageType.PROTO2;
-  }
-
-  protected abstract Object fromReflectionType(Object value);
-  protected abstract Object singularFromReflectionType(Object value);
-  protected abstract Object toReflectionType(Object value);
-  protected abstract Object singularToReflectionType(Object value);
-}