Migrate from android::String isEmpty to empty

This empty method is different from the old one - it aligns with
std::string definition.

Bug: 295394788
Test: make checkbuild
Change-Id: I890b3dfa930002f4406e9d9aec024f94ada1cad0
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index 87da6fa..ad8cdb9 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -6129,7 +6129,7 @@
 
             if (status == NO_ERROR) {
                 const String8& address = String8(device->address().c_str());
-                if (!address.isEmpty()) {
+                if (!address.empty()) {
                     char *param = audio_device_address_to_parameter(device->type(), address);
                     mpClientInterface->setParameters(input, String8(param));
                     free(param);
@@ -7876,7 +7876,7 @@
     sp<DeviceDescriptor> device = devices.getDeviceForOpening();
     const audio_devices_t deviceType = device->type();
     const String8 &address = String8(device->address().c_str());
-    if (!address.isEmpty()) {
+    if (!address.empty()) {
         char *param = audio_device_address_to_parameter(deviceType, address.c_str());
         mpClientInterface->setParameters(output, String8(param));
         free(param);