Switch MDB GrContextOptions over to Enable style

Change-Id: Id6541c346a13649c89ca3b9ccb13972976f9b973
Reviewed-on: https://skia-review.googlesource.com/105603
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/include/gpu/GrContextOptions.h b/include/gpu/GrContextOptions.h
index 0cf4553..338c538 100644
--- a/include/gpu/GrContextOptions.h
+++ b/include/gpu/GrContextOptions.h
@@ -144,14 +144,14 @@
      * Allow Ganesh to explicitly allocate resources at flush time rather than incrementally while
      * drawing. This will eventually just be the way it is but, for now, it is optional.
      */
-    bool fExplicitlyAllocateGPUResources = false;
+    Enable fExplicitlyAllocateGPUResources = Enable::kDefault;
 
     /**
      * Allow Ganesh to sort the opLists prior to allocating resources. This is an optional
      * behavior that is only relevant when 'fExplicitlyAllocateGPUResources' is enabled.
      * Eventually this will just be what is done and will not be optional.
      */
-    bool fSortRenderTargets = false;
+    Enable fSortRenderTargets = Enable::kDefault;
 
     /**
      * Disables correctness workarounds that are enabled for particular GPUs, OSes, or drivers.