remove firstSubRun

Since exposing subRunList, there is no reason to have the additional API
call for getting the head of the list.

Change-Id: Ib4bf8b7b89484154ad8d576bb5397810628f1a11
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/302258
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Auto-Submit: Herb Derby <herb@google.com>
diff --git a/src/gpu/ops/GrAtlasTextOp.cpp b/src/gpu/ops/GrAtlasTextOp.cpp
index 3e016ca..0821bc1 100644
--- a/src/gpu/ops/GrAtlasTextOp.cpp
+++ b/src/gpu/ops/GrAtlasTextOp.cpp
@@ -501,13 +501,13 @@
             glyphRunList, drawMatrix, rtc->surfaceProps(),
             contextPriv.caps()->shaderCaps()->supportsDistanceFieldText(),
             SDFOptions, blob.get());
-    if (!blob->firstSubRun()) {
+    if (!blob->subRunList().head()) {
         return nullptr;
     }
 
     std::unique_ptr<GrDrawOp> op;
     std::tie(std::ignore, op) =
-            blob->firstSubRun()->makeAtlasTextOp(nullptr, mtxProvider, glyphRunList, rtc);
+            blob->subRunList().head()->makeAtlasTextOp(nullptr, mtxProvider, glyphRunList, rtc);
     return op;
 }