delay hosted plugins' initialization

[elaihau]

setup plugin api before plugins are started

• in current Theia code plugins are loaded and activated before the plugin api becomes ready. This change fixes this problem.

Signed-off-by: elaihau liang.huang@ericsson.com

delay hosted plugins' initialization

• When plugins query the workspace.workspaceFolders, Theia plugin api returns undefined when there is no workspace open, or the opened workspace has not been resolved by WorkspaceService. And this is inconsistent with vsCode, where the extension host is not started until the initialize function of WorkspaceService returns. This change delays the initialization and loading of plugins to ensure workspace root(s) are resolved beforehand.

Signed-off-by: elaihau liang.huang@ericsson.com

[elaihau]

in vscode the extension host is started like this:

	enterWorkspace(path: URI): Promise<void> {

		// Stop the extension host first to give extensions most time to shutdown
		this.extensionService.stopExtensionHost();
		let extensionHostStarted: boolean = false;

		const startExtensionHost = () => {
			this.extensionService.startExtensionHost();
			extensionHostStarted = true;
		};

		return this.windowService.enterWorkspace(path).then(result => {

			// Migrate storage and settings if we are to enter a workspace
			if (result) {
				return this.migrate(result.workspace).then(() => {
                                        // ... ...
                                        // ... ...
					const workspaceImpl = this.contextService as WorkspaceService;
					return workspaceImpl.initialize(result.workspace, startExtensionHost);
				});
			}

			return Promise.resolve();
		}).then(undefined, error => {
			if (!extensionHostStarted) {
				startExtensionHost(); // start the extension host if not started
			}

			return Promise.reject(error);
		});

https://github.com/Microsoft/vscode/blob/434407d3d530646cc8a6d57ec8d662465c20f19d/src/vs/workbench/services/workspace/node/workspaceEditingService.ts#L251

Therefore, workspace.workspaceFolders never returns a undefined if the vscode instance is started with an opened workspace / folder

[benoitf]

thx @elaihau

[elaihau]

related to #4216