Adding repeat mode to texture domain

BUG=skia:
R=bsalomon@chromium.org, senorblanco@chromium.org, bsalomon@google.com, junov@chromium.org

Author: joshualitt@chromium.org

Review URL: https://codereview.chromium.org/422123003
diff --git a/src/gpu/effects/GrTextureDomain.h b/src/gpu/effects/GrTextureDomain.h
index 80a617e..7e270f8 100644
--- a/src/gpu/effects/GrTextureDomain.h
+++ b/src/gpu/effects/GrTextureDomain.h
@@ -23,11 +23,18 @@
 class GrTextureDomain {
 public:
     enum Mode {
-        kIgnore_Mode,  // Ignore the texture domain rectangle.
-        kClamp_Mode,   // Clamp texture coords to the domain rectangle.
-        kDecal_Mode,   // Treat the area outside the domain rectangle as fully transparent.
+        // Ignore the texture domain rectangle.
+        kIgnore_Mode,
+        // Clamp texture coords to the domain rectangle.
+        kClamp_Mode,
+        // Treat the area outside the domain rectangle as fully transparent.
+        kDecal_Mode,
+        // Wrap texture coordinates.  NOTE: filtering may not work as expected because Bilerp will
+        // read texels outside of the domain.  We could perform additional texture reads and filter
+        // in the shader, but are not currently doing this for performance reasons
+        kRepeat_Mode,
 
-        kLastMode = kDecal_Mode
+        kLastMode = kRepeat_Mode
     };
     static const int kModeCount = kLastMode + 1;