no one access the results.

		// Send the request.
		$score_request->execute();

		$score_request_no_boost = $this->maybe_dispatch_no_boost_score_request( $url );

		return $this->prepare_speed_score_response( $url, $score_request, $score_request_no_boost );
	}

	/**
	 * Handler for POST /speed-scores-history.
	 *
	 * @param \WP_REST_Request $request The request object.
	 *
	 * @return \WP_REST_Response|\WP_Error The response.
	 */
	public function dispatch_speed_score_graph_history_request( $request ) {
		$score_history_request = new Speed_Score_Graph_History_Request( $request->get_param( 'start' ), $request->get_param( 'end' ), array() );
		// Send the request.
		return $score_history_request->execute();
	}

	/**
	 * Remove the string "jb-disable-module" from array of strings.
	 *
	 * This is intended to be used by the filter `jetpack_boost_excluded_query_parameters` to allow `jb-disable-module` url parameter during score requests.
	 *
	 * @param string[] $params List of parameters to be removed from url.
	 *
	 * @return string[] Revised list of parameters to remove from url.
	 */
	public function allow_jb_disable_module( $params ) {
		$index = array_search( 'jb-disable-modules', $params, true );
		unset( $params[ $index ] );

		return $params;
	}

	/**
	 * Handler for POST /speed-scores.
	 *
	 * @param \WP_REST_Request $request The request object.
	 *
	 * @return \WP_REST_Response|\WP_Error The response.
	 */
	public function fetch_speed_score( $request ) {
		$url = $this->process_url_arg( $request );
		if ( is_wp_error( $url ) ) {
			return $url;
		}

		// Poll update if there is an ongoing request for scores with boost disabled.
		$url_no_boost           = $this->get_boost_modules_disabled_url( $url );
		$score_request_no_boost = $this->get_score_request_by_url( $url_no_boost );
		if ( $score_request_no_boost && $score_request_no_boost->is_pending() ) {
			$response = $score_request_no_boost->poll_update();
			if ( is_wp_error( $response ) ) {
				return $response;
			}
		}

		// Poll update if there is an ongoing request for scores with boost enabled.
		$score_request = $this->get_score_request_by_url( $url );
		if ( $score_request && $score_request->is_pending() ) {
			$response = $score_request->poll_update();
			if ( is_wp_error( $response ) ) {
				return $response;
			}
		}

		// If this is a fresh install, there might not be any speed score history. In which case, we want to fetch the initial scores.
		// While updating plugin from 1.2 -> 1.3, the history will be missing along with a non-pending score request due to data structure change.
		$history = new Speed_Score_History( $url );
		if ( null === $history->latest_scores() && ( empty( $score_request ) || ! $score_request->is_pending() ) ) {
			return $this->dispatch_speed_score_request( $request );
		}

		return $this->prepare_speed_score_response( $url, $score_request, $score_request_no_boost );
	}

	/**
	 * If it is time to fetch the score without boost, fetch it.
	 *
	 * @param string $url Url of the site.
	 *
	 * @return Speed_Score_Request
	 */
	private function maybe_dispatch_no_boost_score_request( $url ) {

		// Allow `jb-disable-module` URL param to fetch score without boost modules being active.
		add_filter( 'jetpack_boost_excluded_query_parameters', array( $this, 'allow_jb_disable_module' ) );

		$url_no_boost = $this->get_boost_modules_disabled_url( $url );

		$history       = new Speed_Score_History( $url_no_boost );
		$score_request = $this->get_score_request_by_url( $url_no_boost );
		if (
			// If there isn't already a pending request.
			( empty( $score_request ) || ! $score_request->is_pending() )
			&& $this->modules->have_enabled_modules()
			&& $history->is_stale()
		) {
			$score_request = new Speed_Score_Request( $url_no_boost, array(), null, 'pending', null, $this->client ); // Dispatch a new speed score request to measure score without boost.
			$score_request->store( 3600 ); // Keep the request for 1 hour even if no one access the results. The value is persisted for 1 hour in wp.com from initial request.

			// Send the request.
			$score_request->execute();
		}
		remove_filter( 'jetpack_boost_excluded_query_parameters', array( $this, 'allow_jb_disable_module' ) );

		return $score_request;
	}

	/**
	 * Get Speed_Score_Request instance by url.
	 *
	 * @param string $url Url to get the Speed_Score_Request instance for.
	 *
	 * @return Speed_Score_Request
	 */
	private function get_score_request_by_url( $url ) {
		return Speed_Score_Request::get(
			Speed_Score_Request::generate_cache_id_from_url( $url )
		);
	}

	/**
	 * Add query parameters to the url that would disable all boost modules.
	 *
	 * @param string $url The original URL we are measuring for score.
	 *
	 * @return string
	 */
	private function get_boost_modules_disabled_url( $url ) {
		return add_query_arg( 'jb-disable-modules', 'all', $url );
	}

	/**
	 * Can the user access speed scores?
	 *
	 * @return bool
	 */
	public function can_access_speed_scores() {
		return current_user_can( 'manage_options' );
	}

	/**
	 * Clear speed score request cache on jetpack_boost_deactivate action.
	 */
	public function clear_speed_score_request_cache() {
		Speed_Score_Request::clear_cache();
	}

	/**
	 * Prepare the speed score response.
	 *
	 * @param string              $url                    URL of the speed is requested for.
	 * @param Speed_Score_Request $score_request          Speed score request.
	 * @param Speed_Score_Request $score_request_no_boost Speed score request without boost enabled.
	 *
	 * @return \WP_Error|\WP_HTTP_Response|\WP_REST_Response
	 */
	private function prepare_speed_score_response( $url, $score_request, $score_request_no_boost ) {
		$history          = new Speed_Score_History( $url );
		$url_no_boost     = $this->get_boost_modules_disabled_url( $url );
		$history_no_boost = new Speed_Score_History( $url_no_boost );

		$response = array();

		if ( ( ! $score_request || $score_request->is_success() ) && ( ! $score_request_no_boost || $score_request_no_boost->is_success() ) ) {
			$response['status'] = 'success';

			$response['scores'] = array(
				'current' => $history->latest_scores(),
				'noBoost' => null,
			);

			// Only include noBoost scores if at least one module is enabled.
			if ( $this->modules->have_enabled_modules() ) {
				$response['scores']['noBoost'] = $history_no_boost->latest_scores();
			}

			$response['scores']['isStale'] = $history->is_stale();

		} elseif ( ( $score_request && $score_request->is_error() ) || ( $score_request_no_boost && $score_request_no_boost->is_error() ) ) {
			// If either request ended up in error, we can just return the one with error so front-end can take action. The relevent url is available on the serialized object.
			if ( $score_request->is_error() ) {
				// Serialized version of score request contains the status property and error description if any.
				$response = $score_request->jsonSerialize();
			} else {
				$response = $score_request_no_boost->jsonSerialize();
			}
		} else {
			// If no request ended up in error/success as previous conditions dictate, it means that either of them are in pending state.
			$response['status'] = 'pending';
		}

		return rest_ensure_response( $response );
	}
}