Non-lazy-decode images are not cached by the cc::ImageDecodeCache.

In  issue 660975  this problem is discussed in the context of avoiding extra uploads for the GpuImageDecodeCache.

This issue is about the fact that the cc::ImageDecodeCache is relied on to cache the results of color conversion. This fails in at least two use cases.

First use case: When the ui::Compositor draws Chrome UI, it does not use lazy-decoded images. As a result, color conversion of these images does not occur, and can be terribly slow (see  issue 769677 ).

Second use case: HTML canvas. Images in canvases are decoded on the main thread, and sometimes are rasterized into tiles. When rasterized into tiles, these images are excluded from the cache because they are already decoded.