webrtc: run tests in the checkout directory

scripts/slave/recipes/webrtc/standalone.expected/client_webrtc_mac64_release__large_tests_.json

 [
   {
     "cmd": [
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/ios/host_info.py",
       "--json-file",
       "/path/to/tmp/json"
     ],
     "name": "host and tools info",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br />OS X 1.2.3, Xcode 6.7.8 (5D342509a)@@@",
@@ skipping 239 matching lines @@
       "@@@STEP_LOG_LINE@json.output (invalid)@null@@@",
       "@@@STEP_LOG_END@json.output (invalid)@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[build::webrtc]/resources/ensure_webcam_is_running.py"
     ],
-    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_",
+    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_/src",
     "name": "webcam_check"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--factory-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--build-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--annotate=gtest",
       "--test-type=audio_device_tests",
       "--step-name=audio_device_tests",
       "--generate-json-file",
       "-o",
       "gtest-results/audio_device_tests",
       "--builder-name=Mac64 Release [large tests]",
       "--slave-name=slavename",
       "--build-number=1337",
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "audio_device_tests"
     ],
-    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_",
+    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_/src",
     "name": "audio_device_tests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--factory-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--build-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--annotate=gtest",
       "--test-type=voe_auto_test",
       "--step-name=voe_auto_test",
       "--generate-json-file",
       "-o",
       "gtest-results/voe_auto_test",
       "--builder-name=Mac64 Release [large tests]",
       "--slave-name=slavename",
       "--build-number=1337",
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "voe_auto_test",
       "--automated"
     ],
-    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_",
+    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_/src",
     "name": "voe_auto_test"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--factory-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--build-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--annotate=gtest",
       "--test-type=video_capture_tests",
       "--step-name=video_capture_tests",
       "--generate-json-file",
       "-o",
       "gtest-results/video_capture_tests",
       "--builder-name=Mac64 Release [large tests]",
       "--slave-name=slavename",
       "--build-number=1337",
       "--revision=f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "video_capture_tests"
     ],
-    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_",
+    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_/src",
     "name": "video_capture_tests"
   },
   {
     "allow_subannotations": true,
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--factory-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--build-properties",
       "{\"BUILD_CONFIG\": \"Release\", \"buildername\": \"Mac64 Release [large tests]\", \"buildnumber\": 1337, \"mastername\": \"client.webrtc\", \"path_config\": \"kitchen\", \"recipe\": \"webrtc/standalone\", \"revision\": \"12345\", \"slavename\": \"slavename\"}",
       "--annotate=graphing",
       "--results-url=https://chromeperf.appspot.com",
       "--perf-dashboard-id=webrtc_perf_tests",
       "--perf-id=webrtc-mac-large-tests",
       "--perf-config",
       "{'a_default_rev': 'r_webrtc_rev'}",
       "--test-type=webrtc_perf_tests",
       "--step-name=webrtc_perf_tests",
       "--builder-name=Mac64 Release [large tests]",
       "--slave-name=slavename",
       "--build-number=1337",
       "--revision=170242",
       "webrtc_perf_tests"
     ],
-    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_",
+    "cwd": "[BUILDER_CACHE]/Mac64_Release__large_tests_/src",
     "name": "webrtc_perf_tests"
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]