Refactor SaveLayer and SaveLayerAlpha

For cc::PaintCanvas::saveLayer[Alpha] and cc::SaveLayer[Alpha]Op,
- Change const PaintFlags* parameter to const PaintFlags&. Only one
  production callsites passed nullptr.
- Add a variant without the bounds parameter, and change the existing
  variant to accept const SkRect& for the bounds parameter.
- Change GraphicsContext::BeginLayer() to be several variants,
  without the bounds parameter. Previously only one caller passed the
  bounds parameter where the bounds didn't matter.
- Remove the branch checking alpha-only flags in RecordPaintCanvas::
  saveLayer() because all important callers know when to call
  saveLayerAlpha().

This makes the callsites clearner, and allows temporary SkRect for
the bounds parameter.

Change-Id: I3d8c81ef17ed26ba26c72f6cfd2a5cc9bea693a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4121362
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Owners-Override: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1086856}

• ash/fast_ink/cursor/cursor_view.cc[diff]
• ash/wallpaper/wallpaper_view.cc[diff]
• cc/paint/discardable_image_map_unittest.cc[diff]
• cc/paint/display_item_list_unittest.cc[diff]
• cc/paint/oop_pixeltest.cc[diff]
• cc/paint/paint_canvas.h[diff]
• cc/paint/paint_flags.cc[diff]
• cc/paint/paint_flags.h[diff]
• cc/paint/paint_op.h[diff]
• cc/paint/paint_op_buffer_serializer.cc[diff]
• cc/paint/paint_op_buffer_unittest.cc[diff]
• cc/paint/paint_op_helper_unittest.cc[diff]
• cc/paint/record_paint_canvas.cc[diff]
• cc/paint/record_paint_canvas.h[diff]
• cc/paint/skia_paint_canvas.cc[diff]
• cc/paint/skia_paint_canvas.h[diff]
• cc/paint/solid_color_analyzer_unittest.cc[diff]
• cc/test/paint_op_helper.h[diff]
• components/paint_preview/renderer/paint_preview_recorder_utils_unittest.cc[diff]
• third_party/blink/renderer/core/paint/box_painter_base.cc[diff]
• third_party/blink/renderer/core/paint/clip_path_clipper.cc[diff]
• third_party/blink/renderer/core/paint/ng/ng_text_painter_base.cc[diff]
• third_party/blink/renderer/core/paint/svg_mask_painter.cc[diff]
• third_party/blink/renderer/core/scroll/scrollbar_theme_mac.cc[diff]
• third_party/blink/renderer/core/svg/graphics/svg_image.cc[diff]
• third_party/blink/renderer/modules/canvas/canvas2d/base_rendering_context_2d.cc[diff]
• third_party/blink/renderer/modules/canvas/canvas2d/base_rendering_context_2d.h[diff]
• third_party/blink/renderer/platform/graphics/compositing/paint_chunks_to_cc_layer.cc[diff]
• third_party/blink/renderer/platform/graphics/crossfade_generated_image.cc[diff]
• third_party/blink/renderer/platform/graphics/graphics_context.cc[diff]
• third_party/blink/renderer/platform/graphics/graphics_context.h[diff]
• third_party/blink/renderer/platform/graphics/paint_generated_image.cc[diff]
• third_party/blink/renderer/platform/graphics/test/mock_paint_canvas.h[diff]
• ui/gfx/canvas.cc[diff]
• ui/views/controls/button/label_button_border.cc[diff]