Make cc/paint have concrete types

cc/paint/paint_recorder.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_RECORDER_H_
 #define CC_PAINT_PAINT_RECORDER_H_
 
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/optional.h"
+#include "cc/paint/paint_canvas.h"
+#include "cc/paint/paint_record.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 
 namespace cc {
-using PaintRecorder = SkPictureRecorder;
-}
+
+class CC_PAINT_EXPORT PaintRecorder {
+ public:
+  PaintRecorder();
+  ~PaintRecorder();
+
+  ALWAYS_INLINE PaintCanvas* beginRecording(const SkRect& bounds) {
+    uint32_t record_flags = 0;
+    canvas_.emplace(recorder_.beginRecording(bounds, nullptr, record_flags));
+    return getRecordingCanvas();
+  }
+
+  ALWAYS_INLINE PaintCanvas* beginRecording(
+      SkScalar width,
+      SkScalar height,
+      SkBBHFactory* rtree_factory = nullptr) {
+    uint32_t record_flags = 0;
+    canvas_.emplace(
+        recorder_.beginRecording(width, height, rtree_factory, record_flags));
+    return getRecordingCanvas();
+  }
+
+  // Only valid between between and finish recording.
+  ALWAYS_INLINE PaintCanvas* getRecordingCanvas() {
+    return canvas_.has_value() ? &canvas_.value() : nullptr;
+  }
+
+  ALWAYS_INLINE sk_sp<PaintRecord> finishRecordingAsPicture(
+      uint32_t end_flags = 0) {
+    sk_sp<SkPicture> picture = recorder_.finishRecordingAsPicture(end_flags);
+    // Some users (e.g. printing) use the existence of the recording canvas
+    // to know if recording is finished, so reset it here.
+    canvas_.reset();

[enne (OOO), 2017/03/03 19:26:10]

Apparently getRecordingCanvas is (reasonably) only be valid between begin/finish
recording, which makes sense.  Printing code depended on this being null after
finish recording, so I added it in.

[danakj, 2017/03/03 19:27:22]

Oh wild, glad Optional makes that easy.

+    return sk_ref_sp(static_cast<PaintRecord*>(picture.get()));
+  }
+
+  ALWAYS_INLINE sk_sp<PaintRecord> finishRecordingAsPictureWithCull(
+      const SkRect& cull_rect,
+      uint32_t end_flags = 0) {
+    sk_sp<SkPicture> picture =
+        recorder_.finishRecordingAsPictureWithCull(cull_rect, end_flags);
+    canvas_.reset();
+    return sk_ref_sp(static_cast<PaintRecord*>(picture.get()));
+  }
+
+ private:
+  SkPictureRecorder recorder_;
+  base::Optional<PaintCanvas> canvas_;
+
+  DISALLOW_COPY_AND_ASSIGN(PaintRecorder);
+};
+
+}  // namespace cc
 
 #endif  // CC_PAINT_PAINT_RECORDER_H_