[mojo-edk] Expose notification source to MojoWatch callbacks

mojo/public/cpp/system/watcher.h

Index: mojo/public/cpp/system/watcher.h
diff --git a/mojo/public/cpp/system/watcher.h b/mojo/public/cpp/system/watcher.h
index cd068aad0b4a6adec6331980aab7dbebc14497d0..6efc700b98a443e2b777bff3d932cf407afe066f 100644
--- a/mojo/public/cpp/system/watcher.h
+++ b/mojo/public/cpp/system/watcher.h
@@ -48,6 +48,11 @@ class Watcher {
   // still active.
   ~Watcher();
 
+  // Allows the watcher to dispatch notifications synchronously if notified on
+  // its own thread. This should be used with caution since it means watched
+  // endpoints may reenter each other.
+  void SetAllowSyncDispatch(bool allowed);
+
   // Indicates if the Watcher is currently watching a handle.
   bool IsWatching() const;
 
@@ -107,6 +112,8 @@ class Watcher {
   // The callback to call when the handle is signaled.
   ReadyCallback callback_;
 
+  bool allow_sync_dispatch_ = false;
+
   base::WeakPtrFactory<Watcher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Watcher);