Add override for obfuscate target to support Proguard.

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 150 matching lines @@
 
         <!-- Zip aligns the APK -->
         <zipalign-helper
           in.package="${out.unaligned.file}"
           out.package="${out.final.file}" />
         <echo level="info">Release Package: ${out.final.file}</echo>
       </sequential>
     </do-only-if-not-library>
     <record-build-info />
   </target>
+
+  <!--
+    Override obfuscate target to pass javac.custom.classpath to Proguard. SDK tools do not provide
+    any way to pass custom class paths to Proguard.
+   -->
+  <target name="-obfuscate">
+    <if condition="${proguard.enabled}">
+      <then>
+        <property name="obfuscate.absolute.dir" location="${out.absolute.dir}/proguard"/>
+        <property name="preobfuscate.jar.file" value="${obfuscate.absolute.dir}/original.jar"/>
+        <property name="obfuscated.jar.file" value="${obfuscate.absolute.dir}/obfuscated.jar"/>
+        <!-- input for dex will be proguard's output -->
+        <property name="out.dex.input.absolute.dir" value="${obfuscated.jar.file}"/>
+
+        <!-- Add Proguard Tasks -->
+        <property name="proguard.jar" location="${android.tools.dir}/proguard/lib/proguard.jar"/>
+        <taskdef name="proguard" classname="proguard.ant.ProGuardTask" classpath="${proguard.jar}"/>
+
+        <!-- Set the android classpath Path object into a single property. It'll be
+                 all the jar files separated by a platform path-separator.
+                 Each path must be quoted if it contains spaces.
+        -->
+        <pathconvert property="project.target.classpath.value" refid="project.target.class.path">
+          <firstmatchmapper>
+            <regexpmapper from='^([^ ]*)( .*)$$' to='"\1\2"'/>
+            <identitymapper/>
+          </firstmatchmapper>
+        </pathconvert>
+
+        <!-- Build a path object with all the jar files that must be obfuscated.
+             This include the project compiled source code and any 3rd party jar
+             files. -->
+        <path id="project.all.classes.path">
+          <pathelement location="${preobfuscate.jar.file}"/>
+          <path refid="project.all.jars.path"/>
+          <!-- Pass javac.custom.classpath for apks. -->
+          <path refid="javac.custom.classpath"/>

[shashi, 2012/10/08 18:50:37]

Relevant change here.

+        </path>
+        <!-- Set the project jar files Path object into a single property. It'll be
+             all the jar files separated by a platform path-separator.
+             Each path must be quoted if it contains spaces.
+        -->
+        <pathconvert property="project.all.classes.value" refid="project.all.classes.path">
+          <firstmatchmapper>
+            <regexpmapper from='^([^ ]*)( .*)$$' to='"\1\2"'/>
+            <identitymapper/>
+          </firstmatchmapper>
+        </pathconvert>
+
+        <!-- Turn the path property ${proguard.config} from an A:B:C property
+             into a series of includes: -include A -include B -include C
+             suitable for processing by the ProGuard task. Note - this does
+             not include the leading '-include "' or the closing '"'; those
+             are added under the <proguard> call below.
+        -->
+        <path id="proguard.configpath">
+          <pathelement path="${proguard.config}"/>
+        </path>
+        <pathconvert pathsep='" -include "' property="proguard.configcmd"
+          refid="proguard.configpath"/>
+
+        <mkdir   dir="${obfuscate.absolute.dir}"/>
+        <delete file="${preobfuscate.jar.file}"/>
+        <delete file="${obfuscated.jar.file}"/>
+        <jar basedir="${out.classes.absolute.dir}"
+          destfile="${preobfuscate.jar.file}"/>
+        <proguard>
+          -include      "${proguard.configcmd}"
+          -include      "${out.absolute.dir}/proguard.txt"
+          -injars       ${project.all.classes.value}
+          -outjars      "${obfuscated.jar.file}"
+          -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>