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

testing/android/native_test_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="replaceme" default="debug" basedir=".">
 
   <description>
     Building native test runner ChromeNativeTests_replaceme.apk
   </description>
 
-  <property environment="env"/>
-  <property name="sdk.dir" location="${env.ANDROID_SDK_ROOT}"/>
-  <property name="sdk.version" value="${env.ANDROID_SDK_VERSION}"/>
-  <property name="toolchain.dir" location="${env.ANDROID_TOOLCHAIN}"/>
-  <property name="src" location="."/>
-  <property name="source.dir" location="java/src"/>
+  <!--
+    TODO(yfriedman): This target can be invoked from multiple depths. So we use ${PRODUCT_DIR} to normalize the paths. This could be cleaned up.
+  -->
+  <import file="${PRODUCT_DIR}/../../build/android/ant/common.xml"/>
+  <import file="${PRODUCT_DIR}/../../build/android/ant/sdk-targets.xml"/>
+  <!--
+    TODO(yfriedman): Remove the need to specify this. We should generate the packages in a way such
+    that it's not required.
+  -->
+  <property name="source.absolute.dir" value="java/src"/>
+  <path id="javac.custom.classpath">
+    <pathelement location="${ANDROID_SDK}/android.jar" />
+  </path>
   <property name="target.abi" value="${APP_ABI}"/>
 
-  <property name="target" value="android-${env.ANDROID_SDK_VERSION}"/>
   <path id="native.libs.gdbserver">
     <fileset file="${toolchain.dir}/../../gdbserver"/>
   </path>
 
-  <condition property="location.base" 
-             value="${sdk.dir}" 
-             else="${sdk.dir}/platforms/android-${sdk.version}">
-    <isset property="env.ANDROID_BUILD_TOP"/>
-  </condition>
-
   <!-- 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>
 
@@ skipping 36 matching lines @@
         <copy todir="${out.dir}/libs/${target.abi}">
           <path refid="native.libs.gdbserver"/>
         </copy>
       </then>
     </if>
   </target>
 
   <import file="${sdk.dir}/tools/ant/build.xml" />
 
 </project>