Rename GrContextFactory::ContextOptions to ContextOverrides

Also changes the behavior of these flags to only override their             
corresponding context options when set, and to leave them unchanged    
when not set.  

BUG=skia:

Change-Id: I09f6be09997594fa888d9045dd4901354ef3f880
Reviewed-on: https://skia-review.googlesource.com/8780
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 6bef230..c25076f 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -843,14 +843,14 @@
     if (gpu_supported()) {
         if (const SkCommandLineConfigGpu* gpuConfig = config->asConfigGpu()) {
             GrContextFactory::ContextType contextType = gpuConfig->getContextType();
-            GrContextFactory::ContextOptions contextOptions = gpuConfig->getContextOptions();
+            GrContextFactory::ContextOverrides contextOverrides = gpuConfig->getContextOverrides();
             GrContextFactory testFactory;
-            if (!testFactory.get(contextType, contextOptions)) {
+            if (!testFactory.get(contextType, contextOverrides)) {
                 info("WARNING: can not create GPU context for config '%s'. "
                      "GM tests will be skipped.\n", gpuConfig->getTag().c_str());
                 return nullptr;
             }
-            return new GPUSink(contextType, contextOptions, gpuConfig->getSamples(),
+            return new GPUSink(contextType, contextOverrides, gpuConfig->getSamples(),
                                gpuConfig->getUseDIText(), gpuConfig->getColorType(),
                                sk_ref_sp(gpuConfig->getColorSpace()), FLAGS_gpu_threading);
         }
@@ -1462,7 +1462,8 @@
                 continue;
             }
         }
-        ContextInfo ctxInfo = factory->getContextInfo(contextType);
+        ContextInfo ctxInfo = factory->getContextInfo(contextType,
+                                                  GrContextFactory::ContextOverrides::kDisableNVPR);
         if (contextTypeFilter && !(*contextTypeFilter)(contextType)) {
             continue;
         }
@@ -1471,7 +1472,7 @@
             (*test)(reporter, ctxInfo);
         }
         ctxInfo = factory->getContextInfo(contextType,
-                                          GrContextFactory::ContextOptions::kEnableNVPR);
+                                          GrContextFactory::ContextOverrides::kRequireNVPRSupport);
         if (ctxInfo.grContext()) {
             (*test)(reporter, ctxInfo);
         }