In  Issue 768108  a new CHROMIUM_texture_storage_image extension was added which allocates GpuMemoryBuffers on the GPU service side. WebGL's DrawingBuffer should be switched to use this extension rather than its current allocation path (CreateImageCHROMIUM / BindTexImage2DCHROMIUM). The only reason to use that path is if CPU-side rendering is going to be done into the GpuMemoryBuffer, which WebGL doesn't.

(CC'ing junov@ and xlai@ in case a similar optimization is possible for 2D canvas.)