Convert ReadData...() to use the new user pointer handling (see r285350).

mojo/system/data_pipe_consumer_dispatcher.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/system/data_pipe_consumer_dispatcher.h"
 
 #include "base/logging.h"
 #include "mojo/system/data_pipe.h"
 #include "mojo/system/memory.h"
 
@@ skipping 33 matching lines @@
   lock().AssertAcquired();
 
   scoped_refptr<DataPipeConsumerDispatcher> rv =
       new DataPipeConsumerDispatcher();
   rv->Init(data_pipe_);
   data_pipe_ = NULL;
   return scoped_refptr<Dispatcher>(rv.get());
 }
 
 MojoResult DataPipeConsumerDispatcher::ReadDataImplNoLock(
-    void* elements,
-    uint32_t* num_bytes,
+    UserPointer<void> elements,
+    UserPointer<uint32_t> num_bytes,
     MojoReadDataFlags flags) {
   lock().AssertAcquired();
 
-  if (!VerifyUserPointer<uint32_t>(num_bytes))
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
   if ((flags & MOJO_READ_DATA_FLAG_DISCARD)) {
     // These flags are mutally exclusive.
     if ((flags & MOJO_READ_DATA_FLAG_QUERY))
       return MOJO_RESULT_INVALID_ARGUMENT;
-    DVLOG_IF(2, elements) << "Discard mode: ignoring non-null |elements|";
+    DVLOG_IF(2, !elements.IsNull())
+        << "Discard mode: ignoring non-null |elements|";
     return data_pipe_->ConsumerDiscardData(
         num_bytes, (flags & MOJO_READ_DATA_FLAG_ALL_OR_NONE));
   }
 
   if ((flags & MOJO_READ_DATA_FLAG_QUERY)) {
     DCHECK(!(flags & MOJO_READ_DATA_FLAG_DISCARD));  // Handled above.
-    DVLOG_IF(2, elements) << "Query mode: ignoring non-null |elements|";
+    DVLOG_IF(2, !elements.IsNull())
+        << "Query mode: ignoring non-null |elements|";
     return data_pipe_->ConsumerQueryData(num_bytes);
   }
 
-  // Only verify |elements| if we're neither discarding nor querying.
-  if (!VerifyUserPointerWithSize<1>(elements, *num_bytes))
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
   return data_pipe_->ConsumerReadData(
       elements, num_bytes, (flags & MOJO_READ_DATA_FLAG_ALL_OR_NONE));
 }
 
 MojoResult DataPipeConsumerDispatcher::BeginReadDataImplNoLock(
     UserPointer<const void*> buffer,
     UserPointer<uint32_t> buffer_num_bytes,
     MojoReadDataFlags flags) {
   lock().AssertAcquired();
 
@@ skipping 26 matching lines @@
   data_pipe_->ConsumerRemoveWaiter(waiter);
 }
 
 bool DataPipeConsumerDispatcher::IsBusyNoLock() const {
   lock().AssertAcquired();
   return data_pipe_->ConsumerIsBusy();
 }
 
 }  // namespace system
 }  // namespace mojo