Add video capture on Android.

media/video/capture/android/video_capture_device_android.h

+// Copyright (c) 2013 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 MEDIA_VIDEO_CAPTURE_ANDROID_VIDEO_CAPTURE_DEVICE_ANDROID_H_
+#define MEDIA_VIDEO_CAPTURE_ANDROID_VIDEO_CAPTURE_DEVICE_ANDROID_H_
+
+#include <jni.h>
+#include <string>
+
+#include "base/android/scoped_java_ref.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread.h"
+#include "media/video/capture/video_capture_device.h"
+
+namespace media {
+
+class VideoCaptureDeviceAndroid : public VideoCaptureDevice {
+ public:
+  virtual ~VideoCaptureDeviceAndroid();
+
+  static VideoCaptureDevice* Create(const Name& device_name);
+  static bool RegisterVideoCaptureDevice(JNIEnv* env);
+
+  // VideoCaptureDevice implementation.
+  virtual void Allocate(int width, int height, int frame_rate,
+                        EventHandler* observer) OVERRIDE;
+  virtual void Start() OVERRIDE;
+  virtual void Stop() OVERRIDE;
+  virtual void DeAllocate() OVERRIDE;
+  virtual const Name& device_name() OVERRIDE;
+
+  // Implement org.chromium.media.VideoCapture.nativeOnFrameAvailable.
+  void OnFrameAvailable(JNIEnv* env, jobject obj,
+      jbyteArray data, jint length,

[Ami GONE FROM CHROMIUM, 2013/01/30 19:46:23]

nit: indent here is wrong (mixing styles again).  Please make style changes in
whole CLs, not just where pointed out.

[wjia(left Chromium), 2013/02/06 00:45:34]

Done.

+      jint rotation, jboolean flip_vert, jboolean flip_horiz);
+
+ private:
+  enum InternalState {
+    kIdle,  // The device is opened but not in use.
+    kAllocated,  // All resouces have been allocated and camera can be started.
+    kCapturing,  // Video is being captured.
+    kError  // Hit error. User needs to recover by destroying the object.
+  };
+
+  explicit VideoCaptureDeviceAndroid(const Name& device_name);
+  bool Init();
+  void SetErrorState(const std::string& reason);
+
+  // Prevent racing on accessing |state_| and |observer_| since both could be
+  // accessed from different threads.

[Ami GONE FROM CHROMIUM, 2013/01/30 19:46:23]

This is less  useful than it could be.  What threads touch this class?  I
believe only the Browser main thread and the Java thread touch this class, and
the Java thread does so only by calling OnFrameAvailable().

If that's true, then you can significantly simplify the implementation by
replacing the locking that happens everywhere with a simple trampoline for OFA()
to post itself back to the UI thread.

If it's not true, then I think you need a class-level header explaining which
threads touch this class and how (e.g. it's not clear why it's ok to
acquire/relinquish/re-acquire the lock in Start(), and expect that two threads
won't have both called the Java start method).

[wjia(left Chromium), 2013/02/06 00:45:34]

Added class-level explanation.

+  base::Lock lock_;
+  InternalState state_;
+  VideoCaptureDevice::EventHandler* observer_;

[Ami GONE FROM CHROMIUM, 2013/01/30 19:46:23]

add a blank line after this to separate the lock_-protected members from the
rest.

[wjia(left Chromium), 2013/02/06 00:45:34]

Done.

+  Name device_name_;
+  VideoCaptureCapability current_settings_;
+  scoped_ptr<uint8[]> rotation_buffer_;
+  int rotation_;
+
+  // Java VideoCaptureAndroid instance.
+  base::android::ScopedJavaGlobalRef<jobject> j_capture_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(VideoCaptureDeviceAndroid);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_VIDEO_CAPTURE_ANDROID_VIDEO_CAPTURE_DEVICE_ANDROID_H_