Make sure the renderer received `$onWillActivateExtension` before proceeding to load extension code

src/vs/workbench/api/browser/mainThreadExtensionService.ts

@@ -50,7 +50,7 @@ export class MainThreadExtensionService implements MainThreadExtensionServiceSha
 	$activateExtension(extensionId: ExtensionIdentifier, reason: ExtensionActivationReason): Promise<void> {
 		return this._extensionService._activateById(extensionId, reason);
 	}
-	$onWillActivateExtension(extensionId: ExtensionIdentifier): void {
+	async $onWillActivateExtension(extensionId: ExtensionIdentifier): Promise<void> {
 		this._extensionService._onWillActivateExtension(extensionId);
 	}
 	$onDidActivateExtension(extensionId: ExtensionIdentifier, codeLoadingTime: number, activateCallTime: number, activateResolvedTime: number, activationReason: ExtensionActivationReason): void {

src/vs/workbench/api/common/extHost.protocol.ts

@@ -830,7 +830,7 @@ export interface MainThreadTaskShape extends IDisposable {
 
 export interface MainThreadExtensionServiceShape extends IDisposable {
 	$activateExtension(extensionId: ExtensionIdentifier, reason: ExtensionActivationReason): Promise<void>;
-	$onWillActivateExtension(extensionId: ExtensionIdentifier): void;
+	$onWillActivateExtension(extensionId: ExtensionIdentifier): Promise<void>;
 	$onDidActivateExtension(extensionId: ExtensionIdentifier, codeLoadingTime: number, activateCallTime: number, activateResolvedTime: number, activationReason: ExtensionActivationReason): void;
 	$onExtensionActivationError(extensionId: ExtensionIdentifier, error: ExtensionActivationError): Promise<void>;
 	$onExtensionRuntimeError(extensionId: ExtensionIdentifier, error: SerializedError): void;

src/vs/workbench/api/common/extHostExtensionService.ts

@@ -303,8 +303,15 @@ export abstract class AbstractExtHostExtensionService extends Disposable impleme
 
 	// --- impl
 
-	private _activateExtension(extensionDescription: IExtensionDescription, reason: ExtensionActivationReason): Promise<ActivatedExtension> {
-		this._mainThreadExtensionsProxy.$onWillActivateExtension(extensionDescription.identifier);
+	private async _activateExtension(extensionDescription: IExtensionDescription, reason: ExtensionActivationReason): Promise<ActivatedExtension> {
+		if (!this._initData.remote.isRemote) {
+			// local extension host process
+			await this._mainThreadExtensionsProxy.$onWillActivateExtension(extensionDescription.identifier);
+		} else {
+			// remote extension host process
+			// do not wait for renderer confirmation
+			this._mainThreadExtensionsProxy.$onWillActivateExtension(extensionDescription.identifier);
+		}
 		return this._doActivateExtension(extensionDescription, reason).then((activatedExtension) => {
 			const activationTimes = activatedExtension.activationTimes;
 			this._mainThreadExtensionsProxy.$onDidActivateExtension(extensionDescription.identifier, activationTimes.codeLoadingTime, activationTimes.activateCallTime, activationTimes.activateResolvedTime, reason);