Provide a GrContextOptions::PersistentCache to Skia

[chinmaygarde]

Implement GrContextOptions::PersistentCache and provide it to Skia GrContextOptions.fPersistentCache. This allows Skia to cache shaders compilations to persistent storage. Even if platforms cache shader bytecode, Skia still has to do some non-trivial amount of work to generate the shader source in the first place. Using the persistent cache allows Skia to avoid repeating this work.

[liyuqian]

@chinmaygarde : are you still actively working on this? One developer is having this issue and posted a very simple reproduction: #813 (comment)

[Hixie]

This won't help first-launch performance, though, right?

[liyuqian]

Yes, it would only help if the app is reopened. We have to compile the shaders at some time.

[Hixie]

Can we compile them at the same time as we compile the Dart code?