Cleanup: Remove internal two-phase data pipe all-or-none support.

mojo/edk/system/local_data_pipe_impl.cc

Index: mojo/edk/system/local_data_pipe_impl.cc
diff --git a/mojo/edk/system/local_data_pipe_impl.cc b/mojo/edk/system/local_data_pipe_impl.cc
index 3d2e9e5f09d1fccd78cf2814eaeb48400b407322..8f878d56a4aef413e50328beb25acbc8ac21794e 100644
--- a/mojo/edk/system/local_data_pipe_impl.cc
+++ b/mojo/edk/system/local_data_pipe_impl.cc
@@ -107,8 +107,7 @@ MojoResult LocalDataPipeImpl::ProducerWriteData(
 
 MojoResult LocalDataPipeImpl::ProducerBeginWriteData(
     UserPointer<void*> buffer,
-    UserPointer<uint32_t> buffer_num_bytes,
-    uint32_t min_num_bytes_to_write) {
+    UserPointer<uint32_t> buffer_num_bytes) {
   DCHECK(consumer_open());
 
   // The index we need to start writing at.
@@ -116,12 +115,6 @@ MojoResult LocalDataPipeImpl::ProducerBeginWriteData(
       (start_index_ + current_num_bytes_) % capacity_num_bytes();
 
   size_t max_num_bytes_to_write = GetMaxNumBytesToWrite();
-  if (min_num_bytes_to_write > max_num_bytes_to_write) {
-    // Don't return "should wait" since you can't wait for a specified amount
-    // of data.
-    return MOJO_RESULT_OUT_OF_RANGE;
-  }
-
   // Don't go into a two-phase write if there's no room.
   if (max_num_bytes_to_write == 0)
     return MOJO_RESULT_SHOULD_WAIT;
@@ -289,16 +282,8 @@ MojoResult LocalDataPipeImpl::ConsumerQueryData(
 
 MojoResult LocalDataPipeImpl::ConsumerBeginReadData(
     UserPointer<const void*> buffer,
-    UserPointer<uint32_t> buffer_num_bytes,
-    uint32_t min_num_bytes_to_read) {
+    UserPointer<uint32_t> buffer_num_bytes) {
   size_t max_num_bytes_to_read = GetMaxNumBytesToRead();
-  if (min_num_bytes_to_read > max_num_bytes_to_read) {
-    // Don't return "should wait" since you can't wait for a specified amount of
-    // data.
-    return producer_open() ? MOJO_RESULT_OUT_OF_RANGE
-                           : MOJO_RESULT_FAILED_PRECONDITION;
-  }
-
   // Don't go into a two-phase read if there's no data.
   if (max_num_bytes_to_read == 0) {
     return producer_open() ? MOJO_RESULT_SHOULD_WAIT