cc: Move SkShader construction to a single spot in PaintShader

cc/paint/paint_shader.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_PAINT_PAINT_SHADER_H_
 #define CC_PAINT_PAINT_SHADER_H_
 
-#include "cc/paint/paint_record.h"
+#include "cc/paint/paint_export.h"
 #include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkScalar.h"
 #include "third_party/skia/include/core/SkShader.h"
 
 namespace cc {
-using PaintShader = SkShader;
 
-inline sk_sp<PaintShader> WrapSkShader(sk_sp<SkShader> shader) {
-  return shader;
-}
+class PaintOpBuffer;
+using PaintRecord = PaintOpBuffer;
 
-inline sk_sp<PaintShader> MakePaintShaderImage(sk_sp<const SkImage> image,
-                                               SkShader::TileMode tx,
-                                               SkShader::TileMode ty,
-                                               const SkMatrix* local_matrix) {
-  return image->makeShader(tx, ty, local_matrix);
-}
+class CC_PAINT_EXPORT PaintShader {
+ public:
+  // Creates a color shader. See SkShader::MakeColorShader.
+  explicit PaintShader(SkColor color);
+  // Creates a linear gradient shader. See SkGradientShader::MakeLinear.
+  PaintShader(const SkPoint points[],
+              const SkColor colors[],
+              const SkScalar pos[],
+              int count,
+              SkShader::TileMode mode,
+              uint32_t flags = 0,
+              const SkMatrix* local_matrix = nullptr);
+  // Creates a radial gradient shader. See SkGradientShader::MakeRadial
+  PaintShader(const SkPoint& center,
+              SkScalar radius,
+              const SkColor colors[],
+              const SkScalar pos[],
+              int color_count,
+              SkShader::TileMode mode,
+              uint32_t flags = 0,
+              const SkMatrix* local_matrix = nullptr);
+  // Creates a two point conical gradient shader. See
+  // SkGradientShader::MakeTwoPointConical.
+  PaintShader(const SkPoint& start,
+              SkScalar start_radius,
+              const SkPoint& end,
+              SkScalar end_radius,
+              const SkColor colors[],
+              const SkScalar pos[],
+              int color_count,
+              SkShader::TileMode mode,
+              uint32_t flags,
+              const SkMatrix* local_matrix);
+  // Creates a sweep gradient shader. See SkGradientShader::MakeSweep.
+  PaintShader(SkScalar cx,
+              SkScalar cy,
+              const SkColor colors[],
+              const SkScalar pos[],
+              int color_count,
+              uint32_t flags,
+              const SkMatrix* local_matrix);
+  // Creates an image shader. See SkImage::makeShader.
+  PaintShader(sk_sp<const SkImage> image,
+              SkShader::TileMode tx,
+              SkShader::TileMode ty,
+              const SkMatrix* local_matrix);
+  // Creates a picture shader. See SkShader::MakePictureShader.
+  PaintShader(sk_sp<PaintRecord> record,
+              SkShader::TileMode tx,
+              SkShader::TileMode ty,
+              const SkMatrix* local_matrix,
+              const SkRect* tile);
+  PaintShader(const PaintShader& other);
+  PaintShader(PaintShader&& other);
+  ~PaintShader();
 
-inline sk_sp<PaintShader> MakePaintShaderRecord(sk_sp<PaintRecord> record,
-                                                SkShader::TileMode tx,
-                                                SkShader::TileMode ty,
-                                                const SkMatrix* local_matrix,
-                                                const SkRect* tile) {
-  return SkShader::MakePictureShader(ToSkPicture(record), tx, ty, local_matrix,
-                                     tile);
-}
+  // TODO(vmpstr): Can we always determine this without constructing an
+  // |sk_shader_|?
+  bool is_valid() const { return !!sk_shader_; }
+  const sk_sp<SkShader>& sk_shader() const { return sk_shader_; }
+
+ private:
+  explicit PaintShader(sk_sp<SkShader> shader);
+
+  sk_sp<SkShader> sk_shader_;
+};
 
 }  // namespace cc
 
 #endif  // CC_PAINT_PAINT_SHADER_H_