Recipes: make cwd default to slave_build

scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json

Index: scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json
diff --git a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json
index 5050601d59079a363c77e207892b67ac63990fdf..df9916dc8e721ae01564989991bb1401fac8ea6c 100644
--- a/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json
+++ b/scripts/slave/recipes/webrtc/standalone.expected/tryserver_webrtc_android_clang.json
@@ -27,6 +27,7 @@
       "--revision",
       "src@12345"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -53,6 +54,7 @@
       "RECIPE_MODULE[webrtc]/resources/cleanup_files.py",
       "[SLAVE_BUILD]/src/out"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "clean test output files"
   },
   {
@@ -65,6 +67,7 @@
       "[SLAVE_BUILD]/src/out/build_product.zip",
       "[SLAVE_BUILD]/src"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "clean local files",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
@@ -89,6 +92,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CROSSCOMPILE": "1",
       "GYP_DEFINES": "OS=android clang=1 component=static_library dcheck_always_on=1 fastbuild=1 gomadir='[BUILD]/goma' target_arch=arm use_goma=1",
@@ -113,6 +117,7 @@
       "[BUILD]/goma",
       "--"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },