chromium_tests: apply chromium.get_env() when running tests

scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json

Index: scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json
diff --git a/scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json b/scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json
index c90cf5e41f0a36e5311f7f43a0f07216e4e0182e..476fb51bfb36c5338193bcc6c931b584670b7397 100644
--- a/scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json
+++ b/scripts/slave/recipes/chromium.expected/full_chromium_webrtc_Mac_Tester.json
@@ -303,6 +303,9 @@
       "--test-launcher-print-test-stdio=always",
       "--test-launcher-bot-mode"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
     "name": "content_browsertests"
   },
   {
@@ -336,6 +339,9 @@
       "--test-launcher-bot-mode",
       "--test-launcher-print-test-stdio=always"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
     "name": "browser_tests"
   },
   {
@@ -360,6 +366,9 @@
       "--build-number=571",
       "content_unittests"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
     "name": "content_unittests"
   },
   {
@@ -389,6 +398,9 @@
       "--test-launcher-jobs=1",
       "--test-launcher-print-test-stdio=always"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
     "name": "media_unittests"
   },
   {
@@ -414,6 +426,9 @@
       "remoting_unittests",
       "--gtest_filter=Webrtc*"
     ],
+    "env": {
+      "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
+    },
     "name": "remoting_unittests"
   },
   {