IVsExtensionManager.Install Method (IInstallableExtension, Boolean)
Installs an extension to the ExtensionsRoot directory.
Assembly: Microsoft.VisualStudio.ExtensionManager (in Microsoft.VisualStudio.ExtensionManager.dll)
The extension to be installed. This must be an extension that was created from a VSIX package.
Specifies whether an extension should be installed on a per-computer basis or only for the current user.
Return ValueType: Microsoft.VisualStudio.ExtensionManager.RestartReason
RestartReason.PendingEnable if a restart of Visual Studio is required; otherwise, RestartReason.None.
Although this API supports the Extension Manager infrastructure, we recommend that you do not use it because it is subject to change.
Installing an extension by using this method automatically enables the extension as well. A restart of Visual Studio may be required for the extension to become loadable.