add header guards

Change-Id: I3680ea31bf279cc6bde58c15a3dfa6b49815cf7e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/225138
Auto-Submit: Hal Canary <halcanary@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>

src/gpu/geometry/GrQuadBuffer.h

@@ -4,6 +4,8 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+#ifndef GrQuadBuffer_DEFINED
+#define GrQuadBuffer_DEFINED
 
 #include "include/private/SkTDArray.h"
 #include "src/gpu/geometry/GrQuad.h"
@@ -373,3 +375,4 @@ bool GrQuadBuffer<T>::MetadataIter::next() {
     // Nothing else is needed to do but report whether or not the updated pointer is valid
     return fCurrentEntry < fBuffer->fData.end();
 }
+#endif  // GrQuadBuffer_DEFINED

src/gpu/ops/GrTextureOp.h

@@ -4,6 +4,8 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+#ifndef GrTextureOp_DEFINED
+#define GrTextureOp_DEFINED
 
 #include "include/core/SkCanvas.h"
 #include "include/core/SkRefCnt.h"
@@ -54,3 +56,4 @@ std::unique_ptr<GrDrawOp> MakeSet(GrRecordingContext*,
                                   sk_sp<GrColorSpaceXform> textureXform);
 
 }
+#endif  // GrTextureOp_DEFINED