Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

ui/gfx/gpu_memory_buffer.cc

 // 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.
 
 #include "ui/gfx/gpu_memory_buffer.h"
 
 #include "base/format_macros.h"
 #include "base/strings/stringprintf.h"
 
 namespace gfx {
 
-base::trace_event::MemoryAllocatorDumpGuid GetGpuMemoryBufferGUIDForTracing(
-    uint64 tracing_process_id,
-    GpuMemoryBufferId buffer_id) {
-  return base::trace_event::MemoryAllocatorDumpGuid(
-      base::StringPrintf("gpumemorybuffer-x-process/%" PRIx64 "/%d",
-                         tracing_process_id, buffer_id));
-}
-
 GpuMemoryBufferHandle::GpuMemoryBufferHandle()
     : type(EMPTY_BUFFER), id(0), handle(base::SharedMemory::NULLHandle()) {
 }
 
 }  // namespace gfx