[Android] Add chrome_java target for building Java code in the chromium layer.

content/shell/android/java/content_shell_apk.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="ContentShell" default="debug" basedir=".">
-
   <description>
     Building ContentShell.apk
   </description>
-
-  <property environment="env"/>
-  <property name="sdk.dir" location="${env.ANDROID_SDK_ROOT}"/>
-  <property name="toolchain.dir" location="${env.ANDROID_TOOLCHAIN}"/>
-  <property name="source.dir" location="src"/>
-  <property name="target" value="android-${env.ANDROID_SDK_VERSION}"/>
-  <property name="target.abi" value="${APP_ABI}"/>
-  <property name="out.dir" location="${PRODUCT_DIR}/content_shell"/>
+  <import file="../../../../build/android/ant/common.xml"/>
+  <import file="../../../../build/android/ant/sdk-targets.xml"/>
+  <property-value name="target.abi" value="${APP_ABI}"/>
+  <property-location name="out.dir" location="${PRODUCT_DIR}/content_shell"
+      check-exists="false"/>
   <property name="resource.absolute.dir" value="../res"/>
   <property name="gen.absolute.dir" value="${out.dir}/gen"/>
+  <property name="jar.libs.dir" value="${out.dir}/java/libs"/>
   <path id="native.libs.gdbserver">
     <fileset file="${toolchain.dir}/../../gdbserver"/>
   </path>
-  <property name="native.libs.absolute.dir" location="${out.dir}/libs" />
-  <property name="asset.absolute.dir" location="${out.dir}/assets" />
+  <property name="native.libs.absolute.dir" location="${out.dir}/libs"/>
+  <property name="asset.absolute.dir" location="${out.dir}/assets"/>
 
   <path id="out.dex.jar.input.ref">
     <fileset file="${out.dir}/java/libs/chromium_content.jar"/>
     <fileset file="${out.dir}/java/libs/chromium_net.jar"/>
     <fileset file="${out.dir}/java/libs/chromium_base.jar"/>
     <fileset file="${out.dir}/java/libs/chromium_media.jar"/>
   </path>
   <property name="java.compilerargs" value="-classpath ${toString:out.dex.jar.input.ref}"/>
 
-  <!-- We expect PRODUCT_DIR to be set like the gyp var
-       (e.g. $ROOT/out/Debug) -->
+  <!-- We expect PRODUCT_DIR to be set like the gyp var (e.g. $ROOT/out/Debug) -->
   <fail message="PRODUCT_DIR env var not set?">
     <condition>
       <not>
         <isset property="PRODUCT_DIR"/>
       </not>
     </condition>
   </fail>
 
   <target name="-post-compile">
-    <!-- copy gdbserver to main libs directory if building debug.
+    <!--
+      Copy gdbserver to main libs directory if building debug.
       TODO(jrg): for now, Chrome on Android always builds native code
       as Release and java/ant as Debug, which means we always install
       gdbserver.  Resolve this discrepancy, possibly by making this
-      Release Official build java/ant as Release. -->
+      Release Official build java/ant as Release.
+    -->
     <if>
       <condition>
-        <equals arg1="${build.target}" arg2="debug" />
+        <equals arg1="${build.target}" arg2="debug"/>
       </condition>
       <then>
-        <echo message="Copying gdbserver to the apk to enable native debugging"/>
+        <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>
   </target>
 
-  <import file="${sdk.dir}/tools/ant/build.xml" />
-
+  <!-- Classpath for javac -->
+  <path id="javac.custom.classpath">
+    <path refid="out.dex.jar.input.ref"/>
+  </path>
+  <import file="${sdk.dir}/tools/ant/build.xml"/>
 </project>