系统Camera和第三方Camera APP 打开Camera时，都能在Camera2ClientBase.cpp中检测到，并且还能看到是哪个APP打开的。

frameworks/av/services/camera/libcameraservice/common/Camera2ClientBase.cpp
//Camera open
Camera2ClientBase<TClientBase>::Camera2ClientBase(
        const sp<CameraService>& cameraService,
        const sp<TCamCallbacks>& remoteCallback,
        const String16& clientPackageName,
        const String8& cameraId,
        int api1CameraId,
        int cameraFacing,
        int clientPid,
        uid_t clientUid,
        int servicePid):
        TClientBase(cameraService, remoteCallback, clientPackageName,
                cameraId, api1CameraId, cameraFacing, clientPid, clientUid, servicePid),
        mSharedCameraCallbacks(remoteCallback),
        mDeviceVersion(cameraService->getDeviceVersion(TClientBase::mCameraIdStr)),
        mDeviceActive(false), mApi1CameraId(api1CameraId)
{
    ALOGI("Camera %s: Opened. Client: %s (PID %d, UID %d)", cameraId.string(),
            String8(clientPackageName).string(), clientPid, clientUid);
	**// add 
	const char* mCameraId = "0";
	const char* mSystemCamera = "com.mediatek.camera";
	if(strcmp(String8(clientPackageName).string(),mSystemCamera) != 0){
		if(strcmp(cameraId.string(),mCameraId) == 0){
			ALOGI("open cameraid %s ,persist.sys.opencamera = true",cameraId.string());
			property_set("persist.sys.opencamera", "true");
		}else{
			ALOGI("open cameraid %s ,persist.sys.opencamera = false",cameraId.string());
			property_set("persist.sys.opencamera", "false");
		}
	}
	//end** 
    mInitialClientPid = clientPid;
    mDevice = new Camera3Device(cameraId);
    LOG_ALWAYS_FATAL_IF(mDevice == 0, "Device should never be NULL here.");
}


//Camera close
template <typename TClientBase>
Camera2ClientBase<TClientBase>::~Camera2ClientBase() {
    ATRACE_CALL();

    TClientBase::mDestructionStarted = true;

    disconnect();
	**// add 
	const char* mSystemCamera = "com.mediatek.camera";
	if(strcmp(String8(TClientBase::mClientPackageName).string(),mSystemCamera) != 0){
		ALOGI("clsoe cameraid %s ,persist.sys.opencamera = false",TClientBase::mCameraIdStr.string());
		property_set("persist.sys.opencamera", "false");
	}
	// end** 
    ALOGI("Closed Camera %s. Client was: %s (PID %d, UID %u)",
            TClientBase::mCameraIdStr.string(),
            String8(TClientBase::mClientPackageName).string(),
            mInitialClientPid, TClientBase::mClientUid);
}