1. A computing device comprising: one or more processing units; and one or more computer-readable storage media comprising computer-executable instructions, which, when executed by the processing units, cause the computing device to: obtain, from network content, an application mapping document identifying one or more applications; obtain, from one or more applications, a manifest identifying one or more collections of network content; generate a first mapping between a first collection of network content and a first application if both the first application comprises a manifest identifying the first collection of network content and if the first collection of network content comprises an application mapping document identifying the first application; and periodically repeating the obtaining the application mapping document and the obtaining the manifest.