Add third_party/android_tools/sdk/platform-tools to PATH if available

tools/test.py

Index: tools/test.py
diff --git a/tools/test.py b/tools/test.py
index 9a32fa597bf68faeae573e8cf4e4210aeff5a12f..8db546e526412172d621bdd763ac72f9b46dc3e8 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -18,6 +18,16 @@ def Main():
   dart_test_script = string.join([tools_dir, dart_script_name], os.sep)
   command = [utils.CheckedInSdkExecutable(),
              '--checked', dart_test_script] + args
+
+  # The testing script potentially needs the android platform tools in PATH so
+  # we do that in ./tools/test.py (a similar logic exists in ./tools/build.py).
+  android_platform_tools = os.path.normpath(os.path.join(
+      tools_dir,
+      '../third_party/android_tools/sdk/platform-tools'))
+  if os.path.isdir(android_platform_tools):
+    os.environ['PATH'] = '%s%s%s' % (
+            os.environ['PATH'], os.pathsep, android_platform_tools)
+
   exit_code = subprocess.call(command)
   utils.DiagnoseExitCode(exit_code, command)
   return exit_code