Add an ONC property for setting per-network roam threshold

This CL maps an  ONC property for setting per-network roam threshold.

BUG=chrome-os-partner:38681
TEST=Expanded test ONC and JSON test sets

Review URL: https://codereview.chromium.org/1087353002

Cr-Commit-Position: refs/heads/master@{#325515}

chromeos/network/onc/onc_signature.cc

@@ -210,6 +210,7 @@ const OncFieldSignature wifi_fields[] = {
     {::onc::wifi::kHexSSID, &kStringSignature},
     {::onc::wifi::kHiddenSSID, &kBoolSignature},
     {::onc::wifi::kPassphrase, &kStringSignature},
+    {::onc::wifi::kRoamThreshold, &kIntegerSignature},
     {::onc::wifi::kSSID, &kStringSignature},
     {::onc::wifi::kSecurity, &kStringSignature},
     {NULL}};

chromeos/network/onc/onc_translation_tables.cc

@@ -120,6 +120,7 @@ const FieldTranslationEntry wifi_fields[] = {
     {::onc::wifi::kHexSSID, shill::kWifiHexSsid},
     {::onc::wifi::kHiddenSSID, shill::kWifiHiddenSsid},
     {::onc::wifi::kPassphrase, shill::kPassphraseProperty},
+    {::onc::wifi::kRoamThreshold, shill::kWifiRoamThresholdProperty},
     // This field is converted during translation, see onc_translator_*.
     // { ::onc::wifi::kSecurity, shill::kSecurityClassProperty },
     {::onc::wifi::kSignalStrength, shill::kSignalStrengthProperty},

chromeos/test/data/network/shill_wifi_psk.json

@@ -8,5 +8,6 @@
    "WiFi.HexSSID": "4F70656E577274", // "OpenWrt"
    "WiFi.HiddenSSID": false,
    "WiFi.Frequency": 2412,
-   "WiFi.FrequencyList": [2412, 5180]
+   "WiFi.FrequencyList": [2412, 5180],
+   "WiFi.RoamThreshold": 20
 }

chromeos/test/data/network/shill_wifi_with_state.json

@@ -13,5 +13,6 @@
    "Type": "wifi",
    "WiFi.BSSID": "00:12:34:ca:56:8b",
    "WiFi.HexSSID": "4F70656E577274", // "OpenWrt"
-   "WiFi.HiddenSSID": false
+   "WiFi.HiddenSSID": false,
+   "WiFi.RoamThreshold": 20
 }

chromeos/test/data/network/translation_of_shill_wifi_with_state.onc

@@ -10,6 +10,7 @@
     "HexSSID": "4F70656E577274", // "OpenWrt"
     "HiddenSSID": false,
     "Passphrase": "some passphrase",
+    "RoamThreshold": 20,
     "SSID": "OpenWrt",
     "Security": "WPA-PSK",
     "SignalStrength": 10

chromeos/test/data/network/valid_wifi_psk.onc

@@ -30,6 +30,7 @@
         "HexSSID": "4F70656E577274", // "OpenWrt"
         "HiddenSSID": false,
         "Passphrase": "some passphrase",
+        "RoamThreshold": 20,
         "Security": "WPA-PSK"
     }
 }

components/onc/docs/onc_spec.html

@@ -724,6 +724,17 @@
       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 we will attempt to roam to a new network. If this
+      value is not set, the default value will be used.
+    </dd>
+
     <dt class="field">Security</dt>
     <dd>
       <span class="field_meta">

components/onc/onc_constants.cc

@@ -208,6 +208,7 @@ const char kFrequencyList[] = "FrequencyList";
 const char kHexSSID[] = "HexSSID";
 const char kHiddenSSID[] = "HiddenSSID";
 const char kPassphrase[] = "Passphrase";
+const char kRoamThreshold[] = "RoamThreshold";
 const char kSSID[] = "SSID";
 const char kSecurity[] = "Security";
 const char kSecurityNone[] = "None";

components/onc/onc_constants.h

@@ -226,6 +226,7 @@ ONC_EXPORT extern const char kFrequencyList[];
 ONC_EXPORT extern const char kHexSSID[];
 ONC_EXPORT extern const char kHiddenSSID[];
 ONC_EXPORT extern const char kPassphrase[];
+ONC_EXPORT extern const char kRoamThreshold[];
 ONC_EXPORT extern const char kSSID[];
 ONC_EXPORT extern const char kSecurity[];
 ONC_EXPORT extern const char kSecurityNone[];