Use SharedPersistentMemoryAllocator to share field trial state

content/browser/gpu/gpu_process_host.h

Index: content/browser/gpu/gpu_process_host.h
diff --git a/content/browser/gpu/gpu_process_host.h b/content/browser/gpu/gpu_process_host.h
index 6fe3a94f3396d1383726d65f94aa5b3d10ac32a8..c4d94fb9bf9734311f2daf4d6afd0f21888e665a 100644
--- a/content/browser/gpu/gpu_process_host.h
+++ b/content/browser/gpu/gpu_process_host.h
@@ -292,12 +292,6 @@ class GpuProcessHost : public BrowserChildProcessHostDelegate,
 
   std::string shader_prefix_key_;
 
-  // Anonymous shared memory segment to share with subprocess containing list of
-  // field trials (represented as a string).
-  // TODO(crbug.com/653874): Eventually remove this and use single shared memory
-  // object across processes.
-  std::unique_ptr<base::SharedMemory> field_trial_state_;
-
   DISALLOW_COPY_AND_ASSIGN(GpuProcessHost);
 };