Enable sandboxing for audio service field trial testing on Windows and Mac.

Bug: 832666
Change-Id: Ic64a983498156bba73c458f2abc872db337d1999
Reviewed-on: https://chromium-review.googlesource.com/1216142Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Marina Ciocea <marinaciocea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589911}

testing/variations/fieldtrial_testing_config.json

@@ -443,13 +443,31 @@
     "AudioService": [
         {
             "platforms": [
-                "linux",
                 "mac",
                 "windows"
             ],
             "experiments": [
                 {
-                    "name": "AudioProcess_LaunchOnStartup_v6",
+                    "name": "AudioProcess_LaunchOnStartup_Sandboxed_v7",
+                    "params": {
+                        "teardown_timeout_s": "0"
+                    },
+                    "enable_features": [
+                        "AudioServiceAudioStreams",
+                        "AudioServiceLaunchOnStartup",
+                        "AudioServiceOutOfProcess",
+                        "AudioServiceSandbox"
+                    ]
+                }
+            ]
+        },
+        {
+            "platforms": [
+                "linux"
+            ],
+            "experiments": [
+                {
+                    "name": "AudioProcess_LaunchOnStartup_v7",
                     "params": {
                         "teardown_timeout_s": "0"
                     },