Fuchsia: Use new call to get thread CPU time

runtime/vm/os_fuchsia.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_OS_FUCHSIA)
 
 #include "vm/os.h"
 
 #include <errno.h>
@@ skipping 81 matching lines @@
 
 
 int64_t OS::GetCurrentMonotonicMicros() {
   int64_t ticks = GetCurrentMonotonicTicks();
   ASSERT(GetCurrentMonotonicFrequency() == kNanosecondsPerSecond);
   return ticks / kNanosecondsPerMicrosecond;
 }
 
 
 int64_t OS::GetCurrentThreadCPUMicros() {
-  UNIMPLEMENTED();
-  return 0;
+  return mx_time_get(MX_CLOCK_THREAD) / kNanosecondsPerMicrosecond;
 }
 
 
 // TODO(5411554):  May need to hoist these architecture dependent code
 // into a architecture specific file e.g: os_ia32_fuchsia.cc
 intptr_t OS::ActivationFrameAlignment() {
 #if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64) ||                   \
     defined(TARGET_ARCH_ARM64)
   const int kMinimumAlignment = 16;
 #elif defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_DBC)
@@ skipping 192 matching lines @@
 }
 
 
 void OS::Exit(int code) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_FUCHSIA)