Revert^2 "Refactor setCurrentProxyScriptUrl to a void method"

setCurrentProxyScriptUrl is used by ProxyTracker which is
included in connectivity service mainline module. To make
this method @SystemApi in follow-up patch, change this
from a boolean method to a void method. Moving the send or
not send broadcast logic to caller because it can know
whether it needs to send a broadcast or not.

The original change was reverted because it broke DeviceOwnerTest
and HostsideVpnTests. The new patch fixes no broadcast sent bug.
The logic was reversed when a PAC file URL is empty so the
broadcast did not send when proxy change.

Bug: 179225084
Bug: 177035719
Test: FrameworksNetTests
      CtsHostsideNetworkTests:HostsideVpnTests#testSetProxy
      CtsHostsideNetworkTests:HostsideVpnTests#testBindToNetworkWithProxy
      CtsHostsideNetworkTests:HostsideVpnTests#testNoProxy
      CtsDevicePolicyManagerTestCases:DeviceOwnerTest#testProxyPacProxyTest
      CtsDevicePolicyManagerTestCases:DeviceOwnerTest#testProxyStaticProxyTest

Change-Id: I029c33913264bfee336a559c4bd048ddd027322b
diff --git a/services/core/java/com/android/server/connectivity/ProxyTracker.java b/services/core/java/com/android/server/connectivity/ProxyTracker.java
index d83ff83..154055a 100644
--- a/services/core/java/com/android/server/connectivity/ProxyTracker.java
+++ b/services/core/java/com/android/server/connectivity/ProxyTracker.java
@@ -226,9 +226,9 @@
         final ProxyInfo defaultProxy = getDefaultProxy();
         final ProxyInfo proxyInfo = null != defaultProxy ?
                 defaultProxy : ProxyInfo.buildDirectProxy("", 0, Collections.emptyList());
+        mPacProxyInstaller.setCurrentProxyScriptUrl(proxyInfo);
 
-        if (mPacProxyInstaller.setCurrentProxyScriptUrl(proxyInfo)
-                == PacProxyInstaller.DONT_SEND_BROADCAST) {
+        if (!shouldSendBroadcast(proxyInfo)) {
             return;
         }
         if (DBG) Log.d(TAG, "sending Proxy Broadcast for " + proxyInfo);
@@ -244,6 +244,10 @@
         }
     }
 
+    private boolean shouldSendBroadcast(ProxyInfo proxy) {
+        return Uri.EMPTY.equals(proxy.getPacFileUrl()) || proxy.getPort() > 0;
+    }
+
     /**
      * Sets the global proxy in memory. Also writes the values to the global settings of the device.
      *