Make WaitableEvent's constructor enum-based.

base/synchronization/waitable_event.h

Index: base/synchronization/waitable_event.h
diff --git a/base/synchronization/waitable_event.h b/base/synchronization/waitable_event.h
index b5d91d00b51fd3b2899f39a4707dcef5ebd3424c..a4ca312174087b4f2a9aec34ebcf31f5507012ef 100644
--- a/base/synchronization/waitable_event.h
+++ b/base/synchronization/waitable_event.h
@@ -43,10 +43,25 @@ class TimeDelta;
 // be better off just using an Windows event directly.
 class BASE_EXPORT WaitableEvent {
  public:
+  // Indicates whether a WaitableEvent should automatically reset the event
+  // state after a single waiting thread has been released or remain signaled
+  // until Reset() is manually invoked.
+  enum class ResetPolicy { MANUAL, AUTOMATIC };
+
+  // Indicates whether a new WaitableEvent should start in a signaled state or
+  // not.
+  enum class InitialState { SIGNALED, NOT_SIGNALED };
+
+  // Constructs a WaitableEvent with policy and initial state as detailed in
+  // the above enums.
+  WaitableEvent(ResetPolicy reset_policy, InitialState initial_state);
+
   // If manual_reset is true, then to set the event state to non-signaled, a
   // consumer must call the Reset method.  If this parameter is false, then the
   // system automatically resets the event state to non-signaled after a single
   // waiting thread has been released.
+  // DEPRECATED: Use the enum-based constructor instead (full removal tracked in
+  // http://crbug.com/612843).
   WaitableEvent(bool manual_reset, bool initially_signaled);
 
 #if defined(OS_WIN)