Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

ui/gfx/gpu_memory_buffer.h

Index: ui/gfx/gpu_memory_buffer.h
diff --git a/ui/gfx/gpu_memory_buffer.h b/ui/gfx/gpu_memory_buffer.h
index 263a0ef41da40ddd140556c2ccc0d73d51a30afe..ba501d56208533d38fe5196e136b136437eac019 100644
--- a/ui/gfx/gpu_memory_buffer.h
+++ b/ui/gfx/gpu_memory_buffer.h
@@ -5,6 +5,7 @@
 #ifndef UI_GFX_GPU_MEMORY_BUFFER_H_
 #define UI_GFX_GPU_MEMORY_BUFFER_H_
 
+#include "base/memory/generic_shared_memory_id.h"
 #include "base/memory/shared_memory.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "build/build_config.h"
@@ -24,7 +25,7 @@ enum GpuMemoryBufferType {
   GPU_MEMORY_BUFFER_TYPE_LAST = OZONE_NATIVE_PIXMAP
 };
 
-using GpuMemoryBufferId = int32;
+using GpuMemoryBufferId = base::memory::GenericSharedMemoryId;
 
 struct GFX_EXPORT GpuMemoryBufferHandle {
   GpuMemoryBufferHandle();