Update from https://crrev.com/327068

base/profiler/native_stack_sampler.h

Index: base/profiler/native_stack_sampler.h
diff --git a/base/profiler/native_stack_sampler.h b/base/profiler/native_stack_sampler.h
new file mode 100644
index 0000000000000000000000000000000000000000..bc170dcf933e6e9bc7554fda261182a142178f75
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+++ b/base/profiler/native_stack_sampler.h
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+// Copyright 2015 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.
+
+#ifndef BASE_PROFILER_NATIVE_STACK_SAMPLER_H_
+#define BASE_PROFILER_NATIVE_STACK_SAMPLER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/profiler/stack_sampling_profiler.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+// NativeStackSampler is an implementation detail of StackSamplingProfiler. It
+// abstracts the native implementation required to record a stack sample for a
+// given thread.
+class NativeStackSampler {
+ public:
+  virtual ~NativeStackSampler();
+
+  // Creates a stack sampler that records samples for |thread_handle|. Returns
+  // null if this platform does not support stack sampling.
+  static scoped_ptr<NativeStackSampler> Create(PlatformThreadId thread_id);
+
+  // The following functions are all called on the SamplingThread (not the
+  // thread being sampled).
+
+  // Notifies the sampler that we're starting to record a new profile. Modules
+  // shared across samples in the profile should be recorded in |modules|.
+  virtual void ProfileRecordingStarting(
+      std::vector<StackSamplingProfiler::Module>* modules) = 0;
+
+  // Records a stack sample to |sample|.
+  virtual void RecordStackSample(StackSamplingProfiler::Sample* sample) = 0;
+
+  // Notifies the sampler that we've stopped recording the current
+  // profile.
+  virtual void ProfileRecordingStopped() = 0;
+
+ protected:
+  NativeStackSampler();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NativeStackSampler);
+};
+
+}  // namespace base
+
+#endif  // BASE_PROFILER_NATIVE_STACK_SAMPLER_H_
+