Extend flags: sharing-qr-code-generator to M85, enable-send-tab-to-self-when-signed-in to M84

Former will be go/no-go'ed for stable by M85, we'll know more about the latter by M84

Change-Id: I6b506c3465c8d7f1e309f219f3e7e4920e7be7e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2067661Reviewed-by: Jeffrey Cohen <jeffreycohen@chromium.org>
Commit-Queue: Travis Skare <skare@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743332}

chrome/browser/flag-metadata.json

@@ -1800,7 +1800,7 @@
   {
     "name": "enable-send-tab-to-self-when-signed-in",
     "owners": [ "//components/send_tab_to_self/OWNERS" ],
-    "expiry_milestone": 78
+    "expiry_milestone": 84
   },
   {
     "name": "enable-service-worker-imported-script-update-check",
@@ -3287,7 +3287,7 @@
   {
     "name": "sharing-qr-code-generator",
     "owners": [ "//components/send_tab_to_self/OWNERS" ],
-    "expiry_milestone": 82
+    "expiry_milestone": 85
   },
   {
     "name": "sharing-rename-devices",