Pepper: remove use of legacy SharedMemory in IPC.

This change the PPB_Buffer_Impl and associated buffer alloc to use
base::UnsafeSharedMemoryRegion instead of the legacy SharedMemoryHandle.
The affected IPCs are PpapiHostMsg_PPBBuffer_Create and
PpapiPluginMsg_VideoCapture_OnDeviceInfo.

Bug: 795291
Change-Id: Ia07e2d2e8c0eea43b898de6f8b33e706226c87b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724084
Reviewed-by: Bill Budge <[email protected]>
Commit-Queue: Matthew Cary (CET) <[email protected]>
Cr-Commit-Position: refs/heads/master@{#682467}
diff --git a/ppapi/proxy/ppb_graphics_3d_proxy.cc b/ppapi/proxy/ppb_graphics_3d_proxy.cc
index e6570939..e7387d5 100644
--- a/ppapi/proxy/ppb_graphics_3d_proxy.cc
+++ b/ppapi/proxy/ppb_graphics_3d_proxy.cc
@@ -294,7 +294,7 @@
     gpu::Capabilities* capabilities,
     SerializedHandle* shared_state,
     gpu::CommandBufferId* command_buffer_id) {
-  shared_state->set_null_shmem();
+  shared_state->set_null_shmem_region();
 
   thunk::EnterResourceCreation enter(instance);