Rename output jar created by apks to have chromium_apk_ prefix.

build/android/ant/sdk-targets.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <!--
   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.
 -->
 <project name="chrome_sdk_overrides" >
   <!--
     Redefinition of targets used by SDK tools.
     Supported version: SDK tools revision 20.
@@ skipping 179 matching lines @@
       <then>
         <echo message="Copying gdbserver to the apk to enable native debugging"/>
         <copy todir="${out.dir}/libs/${target.abi}">
           <path refid="native.libs.gdbserver"/>
         </copy>
       </then>
     </if>
 
     <!-- Package all the compiled .class files into a .jar. -->
     <jar
-      jarfile="${lib.java.dir}/chromium_${PACKAGE_NAME}.jar"
+      jarfile="${lib.java.dir}/chromium_apk_${PACKAGE_NAME}.jar"
       basedir="${out.classes.absolute.dir}"
     />
   </target>
 
   <!--
     Override obfuscate target to pass javac.custom.classpath to Proguard. SDK tools do not provide
     any way to pass custom class paths to Proguard.
    -->
   <target name="-obfuscate">
     <if condition="${proguard.enabled}">
@@ skipping 64 matching lines @@
           -libraryjars  ${project.target.classpath.value}
           -dump         "${obfuscate.absolute.dir}/dump.txt"
           -printseeds   "${obfuscate.absolute.dir}/seeds.txt"
           -printusage   "${obfuscate.absolute.dir}/usage.txt"
           -printmapping "${obfuscate.absolute.dir}/mapping.txt"
         </proguard>
       </then>
     </if>
   </target>
 </project>