Reapply "libprocessgroup: Combine all 3 ActivateControllers imple..."

This reverts commit 0fa49253a484fc0c99d067ade57a4978059b3a95.

Change-Id: I83121ff295caaabc0a2fd8a606ee2d52dacb0174
diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index 83a2258..d3719ee 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -662,10 +662,9 @@
         return -errno;
     }
     if (activate_controllers) {
-        ret = CgroupMap::GetInstance().ActivateControllers(uid_path);
-        if (ret) {
-            LOG(ERROR) << "Failed to activate controllers in " << uid_path;
-            return ret;
+        if (!CgroupMap::GetInstance().ActivateControllers(uid_path)) {
+            PLOG(ERROR) << "Failed to activate controllers in " << uid_path;
+            return -errno;
         }
     }