Cleanup resource flags

Converts GrResourceProvider::Flags and GrResourceCache::ScratchFlags
to "enum class" and fixes a case where we were accidentally using the
wrong type of flag. Makes sure to allocate GrSWMaskHelper proxies with
kNoPendingIO.

Bug: skia:8351
Change-Id: Ibcaa26314a53d0cb31ae22915ab94ab0fc07e76d
Reviewed-on: https://skia-review.googlesource.com/157280
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/tests/ProxyTest.cpp b/tests/ProxyTest.cpp
index 694adf4..5e050a3 100644
--- a/tests/ProxyTest.cpp
+++ b/tests/ProxyTest.cpp
@@ -127,7 +127,8 @@
                             {
                                 sk_sp<GrTexture> tex;
                                 if (SkBackingFit::kApprox == fit) {
-                                    tex = resourceProvider->createApproxTexture(desc, 0);
+                                    tex = resourceProvider->createApproxTexture(
+                                            desc, GrResourceProvider::Flags::kNone);
                                 } else {
                                     tex = resourceProvider->createTexture(desc, budgeted);
                                 }
@@ -160,7 +161,8 @@
                             {
                                 sk_sp<GrTexture> tex;
                                 if (SkBackingFit::kApprox == fit) {
-                                    tex = resourceProvider->createApproxTexture(desc, 0);
+                                    tex = resourceProvider->createApproxTexture(
+                                            desc, GrResourceProvider::Flags::kNone);
                                 } else {
                                     tex = resourceProvider->createTexture(desc, budgeted);
                                 }