1. A method, implemented at least in part by a computing device comprising a display and a graphics processing unit (GPU), for rendering content for display using a plurality of rendering contexts, the method comprising: for a lower priority rendering context of the plurality of rendering contexts: receiving, from a first software component associated with the lower priority rendering context, a plurality of requests to render blocks of content on the display using the GPU, wherein each request is for rendering a specific block of content, and wherein the first software component is a GPU-based renderer; wherein the plurality of requests to render content for the lower priority rendering context are constrained to content having a pre-determined block size; and wherein a lower priority is applied to the plurality of requests to render content for the lower priority rendering context; for a higher priority rendering context of the plurality of rendering contexts: receiving, from a second software component associated with the higher priority rendering context, a plurality of requests to render content on the display using the GPU, and wherein the second software component is responsible for drawing user interface elements on the display and for receiving user interface input from a user of the computing device; wherein the plurality of requests received for the higher priority rendering context are not constrained to content having the pre-determined block size; and wherein a higher priority is applied to the plurality of requests received for the higher priority rendering context; and displaying content on the display of the computing device according to the plurality of requests received for the lower priority rendering context and the plurality of requests received for the higher priority rendering context.