1. A computer system for managing browser storage, comprising: one or more processor; and one or more storage device having stored thereon computer-executable instructions that are executable by the one or more processor to configure the computer system to manage browser storage, including computer-executable instructions that are executable by the one or more processor to configure the computer system to perform at least the following: receive inputs from a non-local source, the inputs specifying: a maximum storage size of an individual application cache specified for each of one or more domains, wherein the individual application cache is configured to store data locally that was obtained via a network from each of one or more websites associated with the one or more domains and which are involved in generating and displaying the one or more websites; a maximum storage size of an individual database cache for each of one or more individual database caches specified for each of the one or more domains, wherein the individual database cache is configured to store data for synchronizing with each of the one or more domains via the network; a maximum storage size of an aggregate application cache, wherein the maximum storage size of the aggregate application cache comprises a total amount of application storage that is permitted to be collectively used for the maximum storage size of all the individual application caches specified for the one or more domains; and a maximum storage size of an aggregate database cache, wherein the maximum storage size of the aggregate database cache comprises a total amount of database storage that is permitted to be collectively used for the maximum storage size of all the individual database caches specified for the one or more domains; set the maximum storage sizes of individual and aggregate application and database caches, respectively, to the sizes specified by the inputs; define a first threshold, wherein the first threshold is below the maximum storage size of the individual application cache specified for each of one or more domains; define a second threshold, wherein the second threshold is below the maximum storage size of the individual database cache specified for each of one or more domains; define a third threshold, wherein the third threshold is below the maximum storage size of the aggregate application cache; define a fourth threshold, wherein the fourth threshold is below the maximum storage size of the aggregate database cache; in response to any of the thresholds being reached, execute a garbage collection technique automatically and without user intervention to determine if at least a portion of data stored is to be deleted based on one or more predefined criteria; and delete at least the portion of the data.