Split NativeThemeAura into Overlay and NonOverlay versions.

ui/native_theme/native_theme_aura_overlay.cc

Index: ui/native_theme/native_theme_aura_overlay.cc
diff --git a/ui/native_theme/native_theme_aura_overlay.cc b/ui/native_theme/native_theme_aura_overlay.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b86ae66294b70fce10bc0224c8d50f728ba2bfaf
--- /dev/null
+++ b/ui/native_theme/native_theme_aura_overlay.cc
@@ -0,0 +1,148 @@
+// Copyright 2016 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.
+
+#include "ui/native_theme/native_theme_aura_overlay.h"
+
+#include "base/trace_event/trace_event.h"
+#include "ui/gfx/skia_util.h"
+#include "ui/native_theme/native_theme_switches.h"
+#include "ui/native_theme/overlay_scrollbar_constants_aura.h"
+
+namespace ui {
+
+namespace {
+
+// Constants for painting overlay scrollbars. Other properties needed outside
+// this painting code are defined in overlay_scrollbar_constants_aura.h.
+constexpr int kOverlayScrollbarStrokeWidth = 1;
+constexpr int kOverlayScrollbarMinimumLength = 12;
+constexpr SkAlpha kOverlayScrollbarAlphaNormal = 0x4D;
+constexpr SkAlpha kOverlayScrollbarAlphaHovered = 0x80;
+constexpr SkAlpha kOverlayScrollbarAlphaPressed = 0x80;
+
+// Indexed by ScrollbarOverlayColorTheme.
+constexpr SkColor kOverlayScrollbarThumbColor[] = {SK_ColorBLACK,
+                                                   SK_ColorWHITE};
+constexpr SkColor kOverlayScrollbarStrokeColor[] = {SK_ColorWHITE,
+                                                    SK_ColorBLACK};
+
+SkAlpha ThumbAlphaForState(NativeTheme::State state) {
+  switch (state) {
+    case NativeTheme::kDisabled:
+      return 0x00;
+    case NativeTheme::kHovered:
+      return kOverlayScrollbarAlphaHovered;
+    case NativeTheme::kNormal:
+      return kOverlayScrollbarAlphaNormal;
+    case NativeTheme::kPressed:
+      return kOverlayScrollbarAlphaPressed;
+    case NativeTheme::kNumStates:
+      break;
+  }
+
+  NOTREACHED();
+  return 0xFF;
+}
+
+}  // namespace
+
+// static
+NativeTheme* NativeTheme::GetInstanceForWeb(bool use_overlay_scrollbars) {
+  if (use_overlay_scrollbars)
+    return NativeThemeAuraOverlay::instance();
+
+  return NativeThemeAura::instance();
+}
+
+// static
+NativeThemeAuraOverlay* NativeThemeAuraOverlay::instance() {
+  CR_DEFINE_STATIC_LOCAL(NativeThemeAuraOverlay, s_native_theme, ());
+  return &s_native_theme;
+}
+
+NativeThemeAuraOverlay::NativeThemeAuraOverlay() {
+  scrollbar_width_ =
+      kOverlayScrollbarThumbWidthPressed + kOverlayScrollbarStrokeWidth * 2;
+}
+
+NativeThemeAuraOverlay::~NativeThemeAuraOverlay() {}
+
+void NativeThemeAuraOverlay::PaintScrollbarTrack(
+    SkCanvas* canvas,
+    Part part,
+    State state,
+    const ScrollbarTrackExtraParams& extra_params,
+    const gfx::Rect& rect) const {
+  NOTREACHED();
+}
+
+void NativeThemeAuraOverlay::PaintScrollbarThumb(
+    SkCanvas* canvas,
+    Part part,
+    State state,
+    const gfx::Rect& rect,
+    ScrollbarOverlayColorTheme theme) const {
+  // Do not paint if state is disabled.
+  if (state == kDisabled)
+    return;
+
+  TRACE_EVENT0("blink", "NativeThemeAuraOverlay::PaintScrollbarThumb");
+
+  gfx::Rect thumb_rect(rect);
+  SkAlpha thumb_alpha = ThumbAlphaForState(state);
+
+  // In overlay mode, draw a stroke (border).
+  {
+    constexpr int kStrokeWidth = kOverlayScrollbarStrokeWidth;
+    SkPaint paint;
+    paint.setColor(
+        SkColorSetA(kOverlayScrollbarStrokeColor[theme], thumb_alpha));
+    paint.setStyle(SkPaint::kStroke_Style);
+    paint.setStrokeWidth(kStrokeWidth);
+    gfx::RectF stroke_rect(thumb_rect);
+    constexpr float kHalfStrokeWidth = kStrokeWidth / 2.f;
+    stroke_rect.Inset(kHalfStrokeWidth, kHalfStrokeWidth);
+    canvas->drawRect(gfx::RectFToSkRect(stroke_rect), paint);
+
+    // Inset the all the edges edges so we fill-in the stroke below.
+    thumb_rect.Inset(kStrokeWidth, kStrokeWidth);
+  }
+
+  SkPaint paint;
+  paint.setColor(SkColorSetA(kOverlayScrollbarThumbColor[theme], thumb_alpha));
+  canvas->drawIRect(gfx::RectToSkIRect(thumb_rect), paint);
+}
+
+void NativeThemeAuraOverlay::PaintScrollbarCorner(SkCanvas* canvas,
+                                           State state,
+                                           const gfx::Rect& rect) const {
+  NOTREACHED();
+}
+
+gfx::Size NativeThemeAuraOverlay::GetPartSize(Part part,
+                                       State state,
+                                       const ExtraParams& extra) const {
+  constexpr int minimum_length =
+      kOverlayScrollbarMinimumLength + 2 * kOverlayScrollbarStrokeWidth;
+
+  // Aura overlay scrollbars need a slight tweak from the base sizes.
+  switch (part) {
+    case kScrollbarHorizontalThumb:
+      return gfx::Size(minimum_length, scrollbar_width_);
+    case kScrollbarVerticalThumb:
+      return gfx::Size(scrollbar_width_, minimum_length);
+    default:
+      // TODO(bokan): We should probably make sure code using overlay
+      // scrollbars isn't asking for part sizes that don't exist. This
+      // currently breaks in Views layout code which indicates they aren't
+      // overlay aware yet. The Views code should be fixed and either this
+      // branch return 0 for parts that don't exist or assert NOTREACHED.
+      // crbug.com/657159.
+      break;
+  }
+
+  return NativeThemeAura::GetPartSize(part, state, extra);
+}
+
+}  // namespace ui