Allow to disable the new scan API for manual network search.

The implementation to attempt new API and then fallback after
error is generic but may be not efficient. For the devices that
is not capable of using new API, it lengthens the network search
because of the new API scan trial in the first place and may fail
if the error is not properly caught.
(Refer to Ifebbac9965a40acaff0d50d32ca8603c72a6a77f for details)

As an alternative, this commit provides a config for devices that
are known as not capable of using new API to disable new API scan
and start network search through old API directly.

Change-Id: Iac3d70d91ee449a3a2ce4e5729176e09cb80b711

res/values/config.xml

@@ -261,4 +261,10 @@
          slot. If true, telephony will always try to place the emergency call on the subscription
          associated with default data first, instead of using the default voice configuration.-->
     <bool name="config_gnss_supl_requires_default_data_for_emergency">false</bool>
+
+    <!-- Flag indicating if network query through TelephonyManager.requestNetworkScan() should be
+         disabled.
+         If set to true, it will send network query through Phone.getAvailableNetworks() directly
+         rather than attempt to query through TelephonyManager.requestNetworkScan() first. -->
+    <bool name="config_disable_TelephonyManager_network_scan">false</bool>
 </resources>

src/com/android/phone/NetworkQueryService.java

@@ -195,6 +195,14 @@ public void startNetworkQuery(
                     switch (mState) {
                         case QUERY_READY:
 
+                            final boolean isRequestNetworkScanDisabled =
+                                    getApplicationContext().getResources().getBoolean(
+                                            R.bool.config_disable_TelephonyManager_network_scan);
+                            if (isRequestNetworkScanDisabled && isIncrementalResult) {
+                                if (DBG) log("network scan via TelephonyManager is disabled");
+                                isIncrementalResult = false;
+                            }
+
                             if (isIncrementalResult) {
                                 if (DBG) log("start network scan via TelephonManager");
                                 TelephonyManager tm = (TelephonyManager) getSystemService(