Add a Finch feature and runtime flag for multidevice.

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index 8bfa8e5f2e3ad2b9305b2a567ba23d45e0b802d2..d9ec512d63d2f8e2d0c00b37029c7e3ef5bfc4a9 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -22117,6 +22117,7 @@ from previous Chrome versions.
   <int value="-2143328006"
       label="enable-fill-on-account-select-no-highlighting"/>
   <int value="-2143113994" label="enable-ephemeral-apps-in-webstore"/>
+  <int value="-2134717874" label="Multidevice:disabled"/>
   <int value="-2134333982" label="ShowArcFilesApp:enabled"/>
   <int value="-2134244069" label="HttpFormWarning:enabled"/>
   <int value="-2132591642" label="enable-input-view"/>
@@ -23191,6 +23192,7 @@ from previous Chrome versions.
   <int value="1511161758" label="BackgroundLoader:enabled"/>
   <int value="1515196403" label="fast-user-switching"/>
   <int value="1517863401" label="history-entry-requires-user-gesture"/>
+  <int value="1533111748" label="Multidevice:enabled"/>
   <int value="1538690515" label="OneGoogleBarOnLocalNtp:enabled"/>
   <int value="1541723759" label="ServiceWorkerNavigationPreload:disabled"/>
   <int value="1548776701" label="AllBookmarks:disabled"/>