Update CommandBufferProxyImpl to mojo shm creation

This changes CommandBufferProxyImpl::AllocateAndMapSharedMemory
to use the new mojo shared memory region API for creating the
unsafe shared memory region it uses.

Bug: 872778
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: Ia1b5380eb21afe54a05e81d26df8307819de23c0
Reviewed-on: https://chromium-review.googlesource.com/1171229Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Alexandr Ilin <alexilin@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Commit-Queue: Matthew Cary <mattcary@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590313}

gpu/ipc/client/command_buffer_proxy_impl.cc

@@ -29,6 +29,7 @@
 #include "gpu/ipc/common/command_buffer_id.h"
 #include "gpu/ipc/common/gpu_messages.h"
 #include "gpu/ipc/common/gpu_param_traits.h"
+#include "mojo/public/cpp/base/shared_memory_utils.h"
 #include "mojo/public/cpp/system/buffer.h"
 #include "mojo/public/cpp/system/platform_handle.h"
 #include "ui/gfx/geometry/size.h"
@@ -698,20 +699,10 @@ bool CommandBufferProxyImpl::Send(IPC::Message* msg) {
 
 std::pair<base::UnsafeSharedMemoryRegion, base::WritableSharedMemoryMapping>
 CommandBufferProxyImpl::AllocateAndMapSharedMemory(size_t size) {
-  mojo::ScopedSharedBufferHandle handle =
-      mojo::SharedBufferHandle::Create(size);
-  if (!handle.is_valid()) {
-    DLOG(ERROR) << "AllocateAndMapSharedMemory: Create failed";
-    return {};
-  }
-
-  // Mojo creates a handle with Writable mode, it needs to be converted to
-  // Unsafe.
   base::UnsafeSharedMemoryRegion region =
-      base::WritableSharedMemoryRegion::ConvertToUnsafe(
-          mojo::UnwrapWritableSharedMemoryRegion(std::move(handle)));
+      mojo::CreateUnsafeSharedMemoryRegion(size);
   if (!region.IsValid()) {
-    DLOG(ERROR) << "AllocateAndMapSharedMemory: Unwrap failed";
+    DLOG(ERROR) << "AllocateAndMapSharedMemory: Allocation failed";
     return {};
   }