Recipes: make cwd default to slave_build

scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json

Index: scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json
diff --git a/scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json b/scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json
index 933e1660226c4025d760f875b79b13bb92508723..a57d834fbc1a711bc11e5739977797879ca08fc1 100644
--- a/scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json
+++ b/scripts/slave/recipes/webrtc/chromium.expected/chromium_webrtc_Linux_Tester_failing_test.json
@@ -21,6 +21,7 @@
       "--revision",
       "src@c321321"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
@@ -75,6 +76,7 @@
       "RECIPE_MODULE[webrtc]/resources/cleanup_files.py",
       "[SLAVE_BUILD]/src/out"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "clean test output files"
   },
   {
@@ -83,6 +85,7 @@
       "-u",
       "[BUILD]/scripts/slave/cleanup_temp.py"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
@@ -92,6 +95,7 @@
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "blink_logging_always_on=1 component=static_library dcheck_always_on=1 gomadir='[BUILD]/goma' target_arch=x64 use_goma=1"
     },
@@ -104,6 +108,7 @@
       "\nimport os, sys\nfrom common import chromium_utils\n\nif os.path.exists(sys.argv[1]):\n  chromium_utils.RemoveDirectory(sys.argv[1])\n",
       "[SLAVE_BUILD]/src/out/Release"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "rmtree build directory",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
@@ -131,6 +136,7 @@
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"Linux Tester\", \"buildnumber\": 571, \"mastername\": \"chromium.webrtc\", \"parent_buildername\": \"Linux Builder\", \"parent_got_revision\": \"c321321\", \"recipe\": \"webrtc/chromium\", \"revision\": null, \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "extract build"
   },
   {
@@ -161,6 +167,7 @@
       "--test-launcher-print-test-stdio=always",
       "--test-launcher-bot-mode"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "content_browsertests"
   },
   {
@@ -193,6 +200,7 @@
       "--test-launcher-bot-mode",
       "--test-launcher-print-test-stdio=always"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "browser_tests",
     "~followup_annotations": [
       "step returned non-zero exit code: 1",
@@ -230,6 +238,7 @@
       "--fake-variations-channel=canary",
       "--force-fieldtrials=WebRTC-NewVideoAPI/Disabled/"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "content_browsertests_old_vie"
   },
   {
@@ -265,6 +274,7 @@
       "--fake-variations-channel=canary",
       "--force-fieldtrials=WebRTC-NewVideoAPI/Disabled/"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "browser_tests_old_vie"
   },
   {
@@ -290,6 +300,7 @@
       "--build-number=571",
       "content_unittests"
     ],
+    "cwd": "[SLAVE_BUILD]",
     "name": "content_unittests"
   },
   {