Add an ONC property for setting per-network roam threshold

components/onc/docs/onc_spec.html

Index: components/onc/docs/onc_spec.html
diff --git a/components/onc/docs/onc_spec.html b/components/onc/docs/onc_spec.html
index a0b89abd1dd2916551c4ca90a4913331dedb7e9b..dd3373f8a45f8149628df86dc0ef5690a21b43b7 100644
--- a/components/onc/docs/onc_spec.html
+++ b/components/onc/docs/onc_spec.html
@@ -724,6 +724,19 @@
       40, 104, 128, or 232 bits.
     </dd>
 
+    <dt class="field">RoamThreshold</dt>
+    <dd>
+      <span class="field_meta">
+        (optional)
+        <span class="type">integer</span>
+      </span>
+      The roam threshold for this network, which is the signal-to-noise value
+      (in dB) below which wpa_supplicant will attempt to roam to a new network.

[pneubeck (no reviews), 2015/04/16 17:10:51]

better remove references to concrete implementations (...the network manager...
is usually fine), like wpa_supplicant, or only mention it as an example.

[samueltan, 2015/04/16 17:41:07]

Done.

+      If this value is not set, the roam threshold for the current WiFi device

[pneubeck (no reviews), 2015/04/16 17:10:51]

these two sentences about the WiFi device's roam threshold don't make sense to
the reader as there is no such setting (i know that there is in Shill).

probably just remove it and talk a bout a 'default' value.

[samueltan, 2015/04/16 17:41:07]

Done. The description is now:

The roam threshold for this network, which is the signal-to-noise value (in dB)
below which we will attempt to roam to a new network. If this value is not set,
the default value will be used.

+      will be used. Otherwise, this value overrides the roam threshold value for
+      the WiFi device.
+    </dd>
+
     <dt class="field">Security</dt>
     <dd>
       <span class="field_meta">