dumpsys: display the client PIDs of all of the services

When gathering info on a service, get the BpBinder handle to look up the
node number of the binder service in binder_logs/proc/<pid>.
Look up the node number in binder_logs/state from the binder service.
That entry in the state file has the client PIDs.

Example output:
$ adb shell dumpsys --clients android.hardware.power.IPower/default
Client PIDs: 437, 708, 203

Test: adb root && adb shell dumpsys --clients
Test: adb shell dumpsys --clients power
Test: adb shell dumpsys --clients --pid
Change-Id: I0daebc18cb9f47925ccec5a3eb0b09c4b1e43fe4
diff --git a/cmds/dumpsys/tests/dumpsys_test.cpp b/cmds/dumpsys/tests/dumpsys_test.cpp
index 312f4d7..fa63db5 100644
--- a/cmds/dumpsys/tests/dumpsys_test.cpp
+++ b/cmds/dumpsys/tests/dumpsys_test.cpp
@@ -627,6 +627,29 @@
     AssertOutputFormat(format);
 }
 
+// Tests 'dumpsys --clients'
+TEST_F(DumpsysTest, ListAllServicesWithClients) {
+    ExpectListServices({"Locksmith", "Valet"});
+    ExpectCheckService("Locksmith");
+    ExpectCheckService("Valet");
+
+    CallMain({"--clients"});
+
+    AssertRunningServices({"Locksmith", "Valet"});
+
+    const std::string format("(.|\n)*((Client PIDs are not available for local binders.)(.|\n)*){2}");
+    AssertOutputFormat(format);
+}
+
+// Tests 'dumpsys --clients service_name'
+TEST_F(DumpsysTest, ListServiceWithClients) {
+    ExpectCheckService("Locksmith");
+
+    CallMain({"--clients", "Locksmith"});
+
+    const std::string format("Client PIDs are not available for local binders.\n");
+    AssertOutputFormat(format);
+}
 // Tests 'dumpsys --thread --stability'
 TEST_F(DumpsysTest, ListAllServicesWithMultipleOptions) {
     ExpectListServices({"Locksmith", "Valet"});