Roll recipe dependencies (nontrivial).

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

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--master",
       "tryserver.webrtc",
       "--builder",
       "linux_gn_rel",
@@ skipping 12 matching lines @@
       "--patchset",
       "1",
       "--rietveld_server",
       "https://fake.rietveld.url",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "src@12345",
       "--output_manifest"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"did_run\": true, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"fixed_revisions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"src\": \"12345\"@@@",
@@ skipping 18 matching lines @@
       "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#170242}\"@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::webrtc]/resources/cleanup_files.py",
       "[SLAVE_BUILD]/src/out"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "clean test output files"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py",
       "--show-path",
       "python",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/cleanup_temp.py"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "cleanup_temp"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[depot_tools]/gclient.py",
       "runhooks"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json",
       "GYP_CHROMIUM_NO_ACTION": "1",
       "GYP_DEFINES": "component=static_library dcheck_always_on=1 fastbuild=1 ffmpeg_branding=Chrome gomadir='[BUILD]/goma' rtc_use_264=1 target_arch=x64 use_goma=1",
       "PATH": "%(PATH)s:RECIPE_PACKAGE_REPO[depot_tools]"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gn.py",
       "--root=[SLAVE_BUILD]/src",
       "gen",
       "//out/Release",
       "--args=ffmpeg_branding=\"Chrome\" rtc_use_h264=true is_debug=false target_cpu=\"x64\" use_goma=true goma_dir=\"[BUILD]/goma\""
     ],
-    "cwd": "[SLAVE_BUILD]",
     "name": "gn"
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py",
       "--show-path",
       "python",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/compile.py",
@@ skipping 15 matching lines @@
       "/path/to/tmp/json",
       "--goma-service-account-json-file",
       "/creds/service_accounts/service-account-goma-client.json",
       "--goma-dir",
       "[BUILD]/goma",
       "--goma-fail-fast",
       "--goma-disable-local-fallback",
       "--",
       "all"
     ],
-    "cwd": "[SLAVE_BUILD]",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "compile",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]