Task manager: Get physical memory efficiently for all processes from SharedSampler

chrome/browser/task_manager/sampling/shared_sampler_posix.cc

 // Copyright 2016 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 "chrome/browser/task_manager/sampling/shared_sampler.h"
 
 #include "content/public/browser/browser_thread.h"
 
 namespace task_manager {
 
 SharedSampler::SharedSampler(
     const scoped_refptr<base::SequencedTaskRunner>& blocking_pool_runner) {}
 
 SharedSampler::~SharedSampler() {}
 
 int64_t SharedSampler::GetSupportedFlags() const { return 0; }
 
 void SharedSampler::RegisterCallbacks(
     base::ProcessId process_id,
-    const OnIdleWakeupsCallback& on_idle_wakeups) {}
+    const OnIdleWakeupsCallback& on_idle_wakeups,
+    const OnPhysicalMemoryCallback& on_physical_memory) {}
 
 void SharedSampler::UnregisterCallbacks(base::ProcessId process_id) {}
 
 void SharedSampler::Refresh(base::ProcessId process_id,
                              int64_t refresh_flags) {}
 
 }  // namespace task_manager