EDK: Add implementation of data pipe consumer read threshold stuff.

mojo/edk/system/data_pipe_impl.h

Index: mojo/edk/system/data_pipe_impl.h
diff --git a/mojo/edk/system/data_pipe_impl.h b/mojo/edk/system/data_pipe_impl.h
index 981ae9e88eb2628a68bb57c4161861398f5c97b2..e92d66cc1a8f1cbc7c5439fea0a44a21de662137 100644
--- a/mojo/edk/system/data_pipe_impl.h
+++ b/mojo/edk/system/data_pipe_impl.h
@@ -144,6 +144,10 @@ class DataPipeImpl {
   bool consumer_open() const MOJO_NO_THREAD_SAFETY_ANALYSIS {
     return owner_->consumer_open_no_lock();
   }
+  size_t consumer_read_threshold_num_bytes() const
+      MOJO_NO_THREAD_SAFETY_ANALYSIS {
+    return owner_->consumer_read_threshold_num_bytes_no_lock();
+  }
   uint32_t producer_two_phase_max_num_bytes_written() const
       MOJO_NO_THREAD_SAFETY_ANALYSIS {
     return owner_->producer_two_phase_max_num_bytes_written_no_lock();