Add gamepad hardware data fetcher, and higher level thread container

content/browser/gamepad/gamepad_provider.h

+// Copyright (c) 2011 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_GAMEPAD_PROVIDER_H_
+#define CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/shared_memory.h"
+#include "base/system_monitor/system_monitor.h"
+#include "base/task.h"
+#include "content/browser/gamepad/data_fetcher.h"
+#include "content/common/gamepad_hardware_buffer.h"
+#include "webkit/glue/gamepad_util.h"
+#if defined(OS_WIN)
+#include "content/browser/gamepad/data_fetcher_win.h"
+#endif
+
+class MessageLoop;
+
+namespace base {
+class Thread;
+}
+
+struct GamepadMsg_Updated_Params;
+
+namespace gamepad {
+
+// Define the default data fetcher that Provider will use if none is supplied.
+// (PlatformDataFetcher).
+#if defined(OS_WIN)
+
+typedef DataFetcherWindows PlatformDataFetcher;
+
+#else
+
+class EmptyDataFetcher {
+ public:
+  void GetGamepadData(WebKit::WebGamepads& pads, bool) {
+    pads.length = 0;
+  }
+};
+typedef EmptyDataFetcher PlatformDataFetcher;
+
+#endif
+
+class Provider : public base::RefCountedThreadSafe<Provider>,
+                 public base::SystemMonitor::DevicesChangedObserver {
+ public:
+  Provider(DataFetcher* fetcher = NULL);

[jam, 2011/11/16 00:24:58]

nit: use explicit and no default parameters, per style guide

[scottmg, 2011/11/16 18:04:35]

Done.

+
+  // Starts or Stops the provider. Called from creator_loop_.
+  void Start();
+  void Stop();
+  base::SharedMemoryHandle GetRendererSharedMemoryHandle(
+      base::ProcessHandle renderer_process);
+
+ private:
+

[jam, 2011/11/16 00:24:58]

nit: no blank line after private

[scottmg, 2011/11/16 18:04:35]

Done.

+  // Method for starting the polling, runs on polling_thread_.
+  void DoInitializePollingThread();
+
+  // Method for polling a DataFetcher. Runs on the polling_thread_.
+  void DoPoll();
+  void ScheduleDoPoll();
+
+  void OnDevicesChanged() OVERRIDE;
+
+  GamepadHardwareBuffer* SharedMemoryAsHardwareBuffer();
+
+  enum { kDesiredSamplingIntervalMs = 16 };
+
+  // The Message Loop on which this object was created.
+  // Typically the I/O loop, but may be something else during testing.
+  MessageLoop* creator_loop_;

[jam, 2011/11/16 00:24:58]

nit: we prefer MessageLoopProxy

[scottmg, 2011/11/16 18:04:35]

Done.

+  scoped_ptr<DataFetcher> provided_fetcher_;
+
+  // When polling_thread_ is running, members below are only to be used
+  // from that thread.
+  scoped_ptr<DataFetcher> data_fetcher_;
+  base::SharedMemory gamepad_shared_memory_;
+  bool devices_changed_;
+
+  // Polling is done on this background thread.
+  scoped_ptr<base::Thread> polling_thread_;
+
+  friend class base::RefCountedThreadSafe<Provider>;

[jam, 2011/11/16 00:24:58]

nit: friend statements usually go right after the private

[scottmg, 2011/11/16 18:04:35]

Done.

+  static Provider* instance_;
+  base::WeakPtrFactory<Provider> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Provider);

[jam, 2011/11/16 00:24:58]

nit: this usually goes last

[scottmg, 2011/11/16 18:04:35]

Done.

+  friend class base::RefCountedThreadSafe<Provider>;

[jam, 2011/11/16 00:24:58]

nit: duplicated

[scottmg, 2011/11/16 18:04:35]

Done.

+  virtual ~Provider();

[jam, 2011/11/16 00:24:58]

nit: functions are listed before variables. usually people list the
constructor/destructor first as well

[scottmg, 2011/11/16 18:04:35]

Done.

+};
+
+}  // namespace gamepad
+
+#endif  // CONTENT_BROWSER_GAMEPAD_PROVIDER_H_