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// Copyright (c) 2012 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 CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_
#define CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_
#include <string>
#include <vector>
#include "base/memory/singleton.h"
namespace content {
class HistogramSubscriber;
// HistogramController is used on the browser process to collect histogram data.
// Only the browser UI thread is allowed to interact with the
// HistogramController object.
class HistogramController {
public:
// Returns the HistogramController object for the current process, or NULL if
// none.
static HistogramController* GetInstance();
// Normally instantiated when the child process is launched. Only one instance
// should be created per process.
HistogramController();
virtual ~HistogramController();
// Register the subscriber so that it will be called when for example
// OnHistogramDataCollected is returning histogram data from a child process.
// This is called on UI thread.
void Register(HistogramSubscriber* subscriber);
// Unregister the subscriber so that it will not be called when for example
// OnHistogramDataCollected is returning histogram data from a child process.
// Safe to call even if caller is not the current subscriber.
void Unregister(const HistogramSubscriber* subscriber);
// Contact all processes and get their histogram data.
void GetHistogramData(int sequence_number);
// Notify the |subscriber_| that it should expect at least |pending_processes|
// additional calls to OnHistogramDataCollected(). OnPendingProcess() may be
// called repeatedly; the last call will have |end| set to true, indicating
// that there is no longer a possibility for the count of pending processes to
// increase. This is called on the UI thread.
void OnPendingProcesses(int sequence_number, int pending_processes, bool end);
// Send the |histogram| back to the |subscriber_|.
// This can be called from any thread.
void OnHistogramDataCollected(
int sequence_number,
const std::vector<std::string>& pickled_histograms);
private:
friend struct base::DefaultSingletonTraits<HistogramController>;
// Contact PLUGIN and GPU child processes and get their histogram data.
// TODO(rtenneti): Enable getting histogram data for other processes like
// PPAPI and NACL.
void GetHistogramDataFromChildProcesses(int sequence_number);
HistogramSubscriber* subscriber_;
DISALLOW_COPY_AND_ASSIGN(HistogramController);
};
} // namespace content
#endif // CONTENT_BROWSER_HISTOGRAM_CONTROLLER_H_