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/audioflinger/PatchPanel.cpp b/services/audioflinger/PatchPanel.cpp
index 972c870..351c618 100644
--- a/services/audioflinger/PatchPanel.cpp
+++ b/services/audioflinger/PatchPanel.cpp
@@ -928,7 +928,7 @@
         }
     }
 
-    if (!patchPanelDump.isEmpty()) {
+    if (!patchPanelDump.empty()) {
         write(fd, patchPanelDump.c_str(), patchPanelDump.size());
     }
 }
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);
diff --git a/services/mediaresourcemanager/ResourceObserverService.cpp b/services/mediaresourcemanager/ResourceObserverService.cpp
index 33525fd..6c5cecf 100644
--- a/services/mediaresourcemanager/ResourceObserverService.cpp
+++ b/services/mediaresourcemanager/ResourceObserverService.cpp
@@ -138,7 +138,7 @@
                 String8 enabledEventsStr;
                 for (auto &event : sEvents) {
                     if (((uint64_t)observable.eventFilter & (uint64_t)event) != 0) {
-                        if (!enabledEventsStr.isEmpty()) {
+                        if (!enabledEventsStr.empty()) {
                             enabledEventsStr.append("|");
                         }
                         enabledEventsStr.append(toString(event).c_str());