mojo/gpu: use SharedBuffer instead of base::SharedMemory with hacks

mojo/public/cpp/system/core.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_SYSTEM_CORE_H_
 #define MOJO_PUBLIC_CPP_SYSTEM_CORE_H_
 
 #include <assert.h>
 #include <stddef.h>
 
@@ skipping 386 matching lines @@
   // will be used).
   shared_buffer->reset(handle);
   return rv;
 }
 
 // TODO(vtl): This (and also the functions below) are templatized to allow for
 // future/other buffer types. A bit "safer" would be to overload this function
 // manually. (The template enforces that the in and out handles to be of the
 // same type.)
 template <class BufferHandleType>
-inline MojoResult DuplicatedBuffer(
+inline MojoResult DuplicateBuffer(
     BufferHandleType buffer,
     const MojoDuplicateBufferHandleOptions* options,
     ScopedHandleBase<BufferHandleType>* new_buffer) {
   assert(new_buffer);
   BufferHandleType handle;
-  MojoResult rv = MojoDuplicateSharedBuffer(buffer.value(), options,
-                                            handle.mutable_value());
+  MojoResult rv = MojoDuplicateBufferHandle(
+      buffer.value(), options, handle.mutable_value());
   // Reset even on failure (reduces the chances that a "stale"/incorrect handle
   // will be used).
   new_buffer->reset(handle);
   return rv;
 }
 
 template <class BufferHandleType>
 inline MojoResult MapBuffer(BufferHandleType buffer,
                             uint64_t offset,
                             uint64_t num_bytes,
                             void** pointer,
                             MojoMapBufferFlags flags) {
-  assert(buffer);
+  assert(buffer.is_valid());
   return MojoMapBuffer(buffer.value(), offset, num_bytes, pointer, flags);
 }
 
 inline MojoResult UnmapBuffer(void* pointer) {
   assert(pointer);
   return MojoUnmapBuffer(pointer);
 }
 
 // A wrapper class that automatically creates a shared buffer and owns the
 // handle.
@@ skipping 20 matching lines @@
       CreateSharedBuffer(&options, num_bytes, &handle);
   assert(result == MOJO_RESULT_OK);
 }
 
 inline SharedBuffer::~SharedBuffer() {
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_SYSTEM_CORE_H_