android: Don't require aapt to be on the path during builds and tests.

build/android/pylib/utils/apk_helper.py

Index: build/android/pylib/utils/apk_helper.py
diff --git a/build/android/pylib/utils/apk_helper.py b/build/android/pylib/utils/apk_helper.py
index fbcc595738f7664275e7410b3f5dba7d6c1db46b..4d8506e2e04f8b73dd7e13f04571cc52132c16c8 100644
--- a/build/android/pylib/utils/apk_helper.py
+++ b/build/android/pylib/utils/apk_helper.py
@@ -4,15 +4,18 @@
 
 """Module containing utilities for apk packages."""
 
+import os.path
 import re
 
 from pylib import cmd_helper
+from pylib import constants
 
 
 def GetPackageName(apk_path):
   """Returns the package name of the apk."""
+  aapt = os.path.join(constants.ANDROID_SDK_TOOLS, 'aapt')
   aapt_output = cmd_helper.GetCmdOutput(
-      ['aapt', 'dump', 'badging', apk_path]).split('\n')
+      [aapt, 'dump', 'badging', apk_path]).split('\n')
   package_name_re = re.compile(r'package: .*name=\'(\S*)\'')
   for line in aapt_output:
     m = package_name_re.match(line)