Recipes: make cwd default to slave_build

scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json

Index: scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json
diff --git a/scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json b/scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json
index 2e16346ef68367eaa0aab0c05ae93855af402e57..be34ff29029ce8a4a7e999f353a795b7aa183550 100644
--- a/scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json
+++ b/scripts/slave/recipes/chromium_gn.expected/full_chromium_webkit_Android_GN__dbg_.json
@@ -24,6 +24,7 @@
       "src/third_party/WebKit@HEAD",
       "--force"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -70,6 +71,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CHROMIUM_NO_ACTION": "1"
     },
@@ -92,6 +94,7 @@
       "[BUILD]/goma",
       "//out/Debug"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "Generate build files"
   },
   {
@@ -102,6 +105,7 @@
       "[SLAVE_BUILD]/src/testing/buildbot/chromium.webkit.json",
       "/path/to/tmp/json"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "read test spec",
     "~followup_annotations": [
       "@@@STEP_TEXT@path: [SLAVE_BUILD]/src/testing/buildbot/chromium.webkit.json@@@",
@@ -134,6 +138,7 @@
       "base_unittests_apk",
       "chrome_shell_apk"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "compile"
   },
   {
@@ -145,6 +150,7 @@
       "check",
       "//out/Debug"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "gn check"
   }
 ]