Field trial for AudioService experiment on Android and ChromeOS

To route audio streams through (in-process) audio service on bots.

Bug: 832666
Change-Id: Ie885b6b725a46e8eeb1859d7abe408c9f4412549
Reviewed-on: https://chromium-review.googlesource.com/1091314
Commit-Queue: Olga Sharonova <olka@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566001}

testing/variations/fieldtrial_testing_config.json

@@ -379,7 +379,7 @@
             ],
             "experiments": [
                 {
-                    "name": "Standalone",
+                    "name": "AudioProcess",
                     "params": {
                         "teardown_timeout_s": "300"
                     },
@@ -389,6 +389,20 @@
                     ]
                 }
             ]
+        },
+        {
+            "platforms": [
+                "android",
+                "chromeos"
+            ],
+            "experiments": [
+                {
+                    "name": "AudioServiceStreams",
+                    "enable_features": [
+                        "AudioServiceAudioStreams"
+                    ]
+                }
+            ]
         }
     ],
     "AutofillCreditCardBankNameDisplay": [