plugin_vm: fixing up flag metadata for microphone and camera

Adding lxj to owners for pluginvm-show-camera-permissions and
plugin-vm-show-microphone-permissions.

Bug: 1106149
Change-Id: Ifcaf168fb48142632098f4ad3206878bc8240880
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2355359Reviewed-by: Jason Lin <lxj@google.com>
Commit-Queue: Jason Lin <lxj@google.com>
Auto-Submit: Daniel Ng <danielng@google.com>
Cr-Commit-Position: refs/heads/master@{#798521}

chrome/browser/flag-metadata.json

@@ -3628,12 +3628,12 @@
   },
   {
     "name": "pluginvm-show-camera-permissions",
-    "owners": [ "danielng" ],
+    "owners": [ "danielng@google.com", "lxj@google.com" ],
     "expiry_milestone": 87
   },
   {
     "name": "pluginvm-show-microphone-permissions",
-    "owners": [ "dtor" ],
+    "owners": [ "dtor", "lxj@google.com" ],
     "expiry_milestone": 87
   },
   {