[android] Adds constants.GetOutDirectory() and converts test scripts to use it.

build/android/pylib/host_driven/test_case.py

Index: build/android/pylib/host_driven/test_case.py
diff --git a/build/android/pylib/host_driven/test_case.py b/build/android/pylib/host_driven/test_case.py
index 4f70508c3d103b4c1852b6eb2429589a451b5564..c2d7880f0a8825844789cb69010b1a63c503e28e 100644
--- a/build/android/pylib/host_driven/test_case.py
+++ b/build/android/pylib/host_driven/test_case.py
@@ -67,9 +67,10 @@ class HostDrivenTestCase(object):
   def TearDown(self):
     pass
 
+  # TODO(craigdh): Remove GetOutDir once references have been removed
+  # downstream.
   def GetOutDir(self):
-    return os.path.join(os.environ['CHROME_SRC'], 'out',
-                        constants.GetBuildType())
+    return constants.GetBuildDirectory()
 
   def Run(self):
     logging.info('Running host-driven test: %s', self.tagged_name)