[//gpu] Create GMB in SIIInProcess::CreateSharedImage(BufferUsage)

This CL changes the GpuMemoryBuffer associated with a MappableSI from
being created on-demand in SIIInProcess::MapSharedImage() to
SIIInProcess::CreateSharedImage(BufferUsage). This matches the behavior
of ClientSII and smoothes the path for moving GMB ownership into
ClientSharedImage.

Bug: 1500611
Change-Id: Ia9df6f85c8d4acb3bb1dbe8c5259744780f0f3c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5029955
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1224793}

gpu/command_buffer/service/shared_image_interface_in_process.cc

@@ -349,6 +349,11 @@ SharedImageInterfaceInProcess::CreateSharedImage(
                        MakeSyncToken(next_fence_sync_release_++)),
         {});
   }
+
+  // Ensure that the GMB is created. This paves the path for an upcoming CL that
+  // will have ClientSharedImage own the GMB.
+  GetGpuMemoryBuffer(mailbox);
+
   return base::MakeRefCounted<ClientSharedImage>(mailbox);
 }