[scheduler] Implement time-based cpu throttling.

third_party/WebKit/Source/platform/scheduler/DEPS

 include_rules = [
+  "+base/atomic_sequence_num.h",
   "+base/atomicops.h",
-  "+base/atomic_sequence_num.h",
   "+base/bind_helpers.h",
   "+base/callback.h",
   "+base/cancelable_callback.h",
   "+base/command_line.h",
   "+base/compiler_specific.h",
   "+base/containers/scoped_ptr_hash_map.h",
   "+base/debug/stack_trace.h",
   "+base/debug/task_annotator.h",
   "+base/feature_list.h",
+  "+base/format_macros.h",
   "+base/logging.h",
   "+base/message_loop/message_loop.h",
   "+base/metrics/field_trial.h",
   "+base/metrics/histogram_macros.h",
+  "+base/optional.h",
   "+base/pending_task.h",
   "+base/run_loop.h",
   "+base/single_thread_task_runner.h",
   "+base/synchronization/lock.h",
   "+base/threading/platform_thread.h",
+  "+base/threading/thread.h",
   "+base/threading/thread_checker.h",
-  "+base/threading/thread.h",
 ]
 
 specific_include_rules = {
   ".*test\.cc": [
     "+testing",
   ],
 }