Move several annotations to annotations package.

base/android/java/src/org/chromium/base/annotations/UsedByReflection.java

 // Copyright 2014 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.
 
-package org.chromium.base;
+package org.chromium.base.annotations;
 
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Target;
 
 /**
  * Annotation used for marking methods and fields that are called by reflection.
  * Useful for keeping components that would otherwise be removed by Proguard.
  * Use the value parameter to mention a file that calls this method.
  *
  * Note that adding this annotation to a method is not enough to guarantee that
  * it is kept - either its class must be referenced elsewhere in the program, or
  * the class must be annotated with this as well.
  */
 @Target({
         ElementType.METHOD, ElementType.FIELD, ElementType.TYPE,
         ElementType.CONSTRUCTOR })
 public @interface UsedByReflection {
     String value();
 }