Make PacProxyService be a system service

PacProxyInstaller class is running a thread all the time and is
listening to intent ACTION_PAC_REFRESH so it would be better to
make it be a system service with a manager class PacProxyManager
which is obtained with getSystemService(PacProxyManager.class).
Besides, rename PacProxyInstaller to PacProxyService will
be easier to know it's the service for PacProxyManager.

ConnectivityService is going to be a mainline module and it
needs constructor of PacProxyService to be SystemApi.
However, in current design, it needs to pass a handler and
an int arguments to the constructor which would be difficult
to maintain if just expose the constructor directly.

So, define a listener for the event that the current PAC
proxy has been installed so that the handler and the int
arguments can be removed from the constructor.

Bug: 177035719
Test: FrameworksNetTests
Change-Id: I2abff75ec59a17628ef006aad348c53fadbed076

services/java/com/android/server/SystemServer.java

@@ -108,6 +108,7 @@ import com.android.server.camera.CameraServiceProxy;
 import com.android.server.clipboard.ClipboardService;
 import com.android.server.compat.PlatformCompat;
 import com.android.server.compat.PlatformCompatNative;
+import com.android.server.connectivity.PacProxyService;
 import com.android.server.contentcapture.ContentCaptureManagerInternal;
 import com.android.server.coverage.CoverageService;
 import com.android.server.devicepolicy.DevicePolicyManagerService;
@@ -1115,6 +1116,7 @@ public final class SystemServer {
         ConsumerIrService consumerIr = null;
         MmsServiceBroker mmsService = null;
         HardwarePropertiesManagerService hardwarePropertiesService = null;
+        PacProxyService pacProxyService = null;
 
         boolean disableSystemTextClassifier = SystemProperties.getBoolean(
                 "config.disable_systemtextclassifier", false);
@@ -1623,6 +1625,15 @@ public final class SystemServer {
                 t.traceEnd();
             }
 
+            t.traceBegin("StartPacProxyService");
+            try {
+                pacProxyService = new PacProxyService(context);
+                ServiceManager.addService(Context.PAC_PROXY_SERVICE, pacProxyService);
+            } catch (Throwable e) {
+                reportWtf("starting PacProxyService", e);
+            }
+            t.traceEnd();
+
             t.traceBegin("StartConnectivityService");
             // This has to be called after NetworkManagementService, NetworkStatsService
             // and NetworkPolicyManager because ConnectivityService needs to take these