Make uncached textures uncached from the get go.

This avoids the problem of a newly created uncached texture causing a purge of cached resources.

BUG=chromium:445885

Review URL: https://codereview.chromium.org/846303002
diff --git a/src/gpu/GrDistanceFieldTextContext.cpp b/src/gpu/GrDistanceFieldTextContext.cpp
index 69dcaa7..1480975 100755
--- a/src/gpu/GrDistanceFieldTextContext.cpp
+++ b/src/gpu/GrDistanceFieldTextContext.cpp
@@ -188,7 +188,7 @@
         desc.fHeight = height;
         desc.fConfig = kAlpha_8_GrPixelConfig;
 
-        *gammaTexture = context->getGpu()->createTexture(desc, NULL, 0);
+        *gammaTexture = context->getGpu()->createTexture(desc, true, NULL, 0);
         if (NULL == *gammaTexture) {
             return;
         }