gpu: Enable SKSL -> GLSL disk caching.

We currently disable using GrContextOptions::PersistentCache if program
binary caching needs to be disabled for a workaround. Since skia can now
be configured to enable caching the SKSL -> GLSL conversion while
disabling program binary caching, allow the persistent cache to be used
for that.

R=ericrk@chromium.org

Bug: 924572
Change-Id: Iad1f60ae7c59809e20b3a5c9c54afd54aa825c63
Reviewed-on: https://chromium-review.googlesource.com/c/1476061
Auto-Submit: Khushal <khushalsagar@chromium.org>
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632839}

gpu/command_buffer/service/shared_context_state.cc

@@ -111,6 +111,7 @@ void SharedContextState::InitializeGrContext(
     options.fGlyphCacheTextureMaximumBytes = glyph_cache_max_texture_bytes_;
     options.fPersistentCache = cache;
     options.fAvoidStencilBuffers = workarounds.avoid_stencil_buffers;
+    options.fDisallowGLSLBinaryCaching = workarounds.disable_program_disk_cache;
     owned_gr_context_ = GrContext::MakeGL(std::move(interface), options);
     gr_context_ = owned_gr_context_.get();
     if (!gr_context_) {

gpu/ipc/service/gpu_channel_manager.cc

@@ -97,8 +97,7 @@ GpuChannelManager::GpuChannelManager(
        gpu::kGpuFeatureStatusEnabled) ||
       features::IsUsingSkiaRenderer();
   const bool disable_disk_cache =
-      gpu_preferences_.disable_gpu_shader_disk_cache ||
-      gpu_driver_bug_workarounds_.disable_program_disk_cache;
+      gpu_preferences_.disable_gpu_shader_disk_cache;
   if (enable_gr_shader_cache && !disable_disk_cache)
     gr_shader_cache_.emplace(gpu_preferences.gpu_program_cache_size, this);
 }