android: camera_device: Replace running_ with CameraState

The CameraDevice class maintains the camera state in the 'running_'
boolean flag to check if the camera has to be started at the first
received process_capture_request() call which happens after the camera
had been stopped.

So far this was correct, as the operations that change the camera
could only start or stop the camera, so a simple boolean flag
was enough.

To prepare to handle the flush() operation that will introduce a new
'flushing' state, replace the simple plain boolean flag with an
enumeration of values that define the CameraState.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/android/camera_device.h

@@ -89,6 +89,11 @@ private:
 		int androidFormat;
 	};
 
+	enum class State {
+		Stopped,
+		Running,
+	};
+
 	void stop();
 
 	int initializeStreamConfigurations();
@@ -115,7 +120,8 @@ private:
 
 	CameraWorker worker_;
 
-	bool running_;
+	State state_;
+
 	std::shared_ptr<libcamera::Camera> camera_;
 	std::unique_ptr<libcamera::CameraConfiguration> config_;