Use std::unique_ptr instead of UniquePtr.

Bug: http://b/22403888
Change-Id: I398fa43b8f33c9281d7ff238521d75f1dcb8a5e7
diff --git a/libutils/CallStack.cpp b/libutils/CallStack.cpp
index 0bfb520..699da74 100644
--- a/libutils/CallStack.cpp
+++ b/libutils/CallStack.cpp
@@ -16,11 +16,12 @@
 
 #define LOG_TAG "CallStack"
 
+#include <memory>
+
 #include <utils/CallStack.h>
 #include <utils/Printer.h>
 #include <utils/Errors.h>
 #include <utils/Log.h>
-#include <UniquePtr.h>
 
 #include <backtrace/Backtrace.h>
 
@@ -40,7 +41,7 @@
 void CallStack::update(int32_t ignoreDepth, pid_t tid) {
     mFrameLines.clear();
 
-    UniquePtr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS, tid));
+    std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS, tid));
     if (!backtrace->Unwind(ignoreDepth)) {
         ALOGW("%s: Failed to unwind callstack.", __FUNCTION__);
     }