Remove use_solid_color_scrollbars pref and settings (blink side)

It didn't work by itself. It was just a redundant information of
whether the scrollbar theme supports solid color scrollbars.

Change-Id: Ib5f59fbc30ef8ef83a2e0b9b36729214ca68ce2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894433
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712010}

third_party/blink/public/web/web_settings.h

@@ -260,7 +260,8 @@ class WebSettings {
   virtual void SetBarrelButtonForDragEnabled(bool) = 0;
   virtual void SetUseLegacyBackgroundSizeShorthandBehavior(bool) = 0;
   virtual void SetViewportStyle(WebViewportStyle) = 0;
-  virtual void SetUseSolidColorScrollbars(bool) = 0;
+  // TODO(wangxianzhu): Remove this function when removing chrome side caller.
+  void SetUseSolidColorScrollbars(bool) {}
   virtual void SetUseWideViewport(bool) = 0;
   virtual void SetV8CacheOptions(V8CacheOptions) = 0;
   virtual void SetValidationMessageTimerMagnification(int) = 0;

third_party/blink/renderer/core/exported/web_settings_impl.cc

@@ -656,10 +656,6 @@ void WebSettingsImpl::SetSmartInsertDeleteEnabled(bool enabled) {
   settings_->SetSmartInsertDeleteEnabled(enabled);
 }
 
-void WebSettingsImpl::SetUseSolidColorScrollbars(bool enabled) {
-  settings_->SetUseSolidColorScrollbars(enabled);
-}
-
 void WebSettingsImpl::SetMainFrameResizesAreOrientationChanges(bool enabled) {
   dev_tools_emulator_->SetMainFrameResizesAreOrientationChanges(enabled);
 }

third_party/blink/renderer/core/exported/web_settings_impl.h

@@ -182,7 +182,6 @@ class CORE_EXPORT WebSettingsImpl final : public WebSettings {
   void SetBarrelButtonForDragEnabled(bool) override;
   void SetUseLegacyBackgroundSizeShorthandBehavior(bool) override;
   void SetViewportStyle(WebViewportStyle) override;
-  void SetUseSolidColorScrollbars(bool) override;
   void SetUseWideViewport(bool) override;
   void SetV8CacheOptions(V8CacheOptions) override;
   void SetValidationMessageTimerMagnification(int) override;

third_party/blink/renderer/core/frame/settings.json5

@@ -450,14 +450,6 @@
       initial: false,
     },
 
-    // If true, scrollers will use overlay scrollbars.  These do not take up any
-    // layout width, are drawn using solid color quads by the compositor, and fade away
-    // after a timeout.
-    {
-      name: "useSolidColorScrollbars",
-      initial: false,
-    },
-
     // The rubber-band overscroll effect is implemented in Blink and is being moved
     // to the compositor thread. This will be set to true and eventually removed.
     // crbug.com/133097

third_party/blink/renderer/core/inspector/dev_tools_emulator.cc

@@ -69,7 +69,6 @@ DevToolsEmulator::DevToolsEmulator(WebViewImpl* web_view)
       is_mobile_layout_theme_enabled_(false),
       original_default_minimum_page_scale_factor_(0),
       original_default_maximum_page_scale_factor_(0),
-      use_solid_color_scrollbar_(false),
       embedder_text_autosizing_enabled_(
           web_view->GetPage()->GetSettings().TextAutosizingEnabled()),
       embedder_device_scale_adjustment_(
@@ -302,9 +301,6 @@ void DevToolsEmulator::EnableMobileEmulation() {
   RuntimeEnabledFeatures::SetMobileLayoutThemeEnabled(true);
   ComputedStyle::InvalidateInitialStyle();
   web_view_->GetPage()->GetSettings().SetForceAndroidOverlayScrollbar(true);
-  use_solid_color_scrollbar_ =
-      web_view_->GetPage()->GetSettings().GetUseSolidColorScrollbars();
-  web_view_->GetPage()->GetSettings().SetUseSolidColorScrollbars(true);
   web_view_->GetPage()->GetSettings().SetViewportStyle(
       WebViewportStyle::kMobile);
   web_view_->GetPage()->GetSettings().SetViewportEnabled(true);
@@ -341,8 +337,6 @@ void DevToolsEmulator::DisableMobileEmulation() {
   RuntimeEnabledFeatures::SetMobileLayoutThemeEnabled(
       is_mobile_layout_theme_enabled_);
   ComputedStyle::InvalidateInitialStyle();
-  web_view_->GetPage()->GetSettings().SetUseSolidColorScrollbars(
-      use_solid_color_scrollbar_);
   web_view_->GetPage()->GetSettings().SetForceAndroidOverlayScrollbar(false);
   web_view_->GetPage()->GetSettings().SetViewportEnabled(false);
   web_view_->GetPage()->GetSettings().SetViewportMetaEnabled(false);

third_party/blink/renderer/core/inspector/dev_tools_emulator.h

@@ -118,7 +118,6 @@ class CORE_EXPORT DevToolsEmulator final
   bool is_mobile_layout_theme_enabled_;
   float original_default_minimum_page_scale_factor_;
   float original_default_maximum_page_scale_factor_;
-  bool use_solid_color_scrollbar_;
   bool embedder_text_autosizing_enabled_;
   float embedder_device_scale_adjustment_;
   bool embedder_prefer_compositing_to_lcd_text_enabled_;

third_party/blink/renderer/core/page/scrolling/scrolling_coordinator.cc

@@ -42,7 +42,6 @@
 #include "third_party/blink/renderer/core/frame/local_frame_ukm_aggregator.h"
 #include "third_party/blink/renderer/core/frame/local_frame_view.h"
 #include "third_party/blink/renderer/core/frame/page_scale_constraints_set.h"
-#include "third_party/blink/renderer/core/frame/settings.h"
 #include "third_party/blink/renderer/core/frame/visual_viewport.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
 #include "third_party/blink/renderer/core/page/chrome_client.h"
@@ -358,10 +357,8 @@ void ScrollingCoordinator::ScrollableAreaScrollbarLayerDidChange(
     cc::ScrollbarLayerBase* scrollbar_layer =
         GetScrollbarLayer(scrollable_area, orientation);
     if (!scrollbar_layer) {
-      Settings* settings = page_->MainFrame()->GetSettings();
-
       scoped_refptr<cc::ScrollbarLayerBase> new_scrollbar_layer;
-      if (settings->GetUseSolidColorScrollbars()) {
+      if (scrollbar.IsSolidColor()) {
         DCHECK(scrollbar.IsOverlayScrollbar());
         new_scrollbar_layer = CreateSolidColorScrollbarLayer(
             orientation, scrollbar.GetTheme().ThumbThickness(scrollbar),

third_party/blink/renderer/core/scroll/scrollbar.cc

@@ -678,6 +678,10 @@ int Scrollbar::ScrollbarThickness() const {
       scrollable_area_->GetLayoutBox()->GetFrame(), theme_scrollbar_thickness_);
 }
 
+bool Scrollbar::IsSolidColor() const {
+  return theme_.IsSolidColor();
+}
+
 bool Scrollbar::IsOverlayScrollbar() const {
   return theme_.UsesOverlayScrollbars();
 }

third_party/blink/renderer/core/scroll/scrollbar.h

@@ -127,6 +127,7 @@ class CORE_EXPORT Scrollbar : public GarbageCollected<Scrollbar>,
 
   void Paint(GraphicsContext&, const CullRect&) const;
 
+  virtual bool IsSolidColor() const;
   virtual bool IsOverlayScrollbar() const;
   bool ShouldParticipateInHitTesting();
 

third_party/blink/renderer/core/scroll/scrollbar_theme.h

@@ -72,6 +72,7 @@ class CORE_EXPORT ScrollbarTheme {
     return kWebScrollbarButtonsPlacementSingle;
   }
 
+  virtual bool IsSolidColor() const { return false; }
   virtual bool UsesOverlayScrollbars() const { return false; }
   virtual void UpdateScrollbarOverlayColorTheme(const Scrollbar&) {}
 

third_party/blink/renderer/core/scroll/scrollbar_theme_overlay_mobile.h

@@ -19,6 +19,7 @@ class CORE_EXPORT ScrollbarThemeOverlayMobile : public ScrollbarThemeOverlay {
   ScrollbarPart HitTest(const Scrollbar&, const IntPoint&) override {
     return kNoPart;
   }
+  bool IsSolidColor() const override { return true; }
   bool UsesNinePatchThumbResource() const override { return false; }
 
  protected:

third_party/blink/renderer/core/scroll/scrollbar_theme_overlay_mock.h

@@ -38,8 +38,12 @@ namespace blink {
 class CORE_EXPORT ScrollbarThemeOverlayMock
     : public ScrollbarThemeOverlayMobile {
  public:
+  // These parameters should be the same as those used by
+  // cc::SolidColorScrollbarLayerImpl to make sure composited and
+  // non-composited scrollbars have the same appearance for tests using mock
+  // overlay scrollbars.
   ScrollbarThemeOverlayMock()
-      : ScrollbarThemeOverlayMobile(3, 4, Color(128, 128, 128)) {}
+      : ScrollbarThemeOverlayMobile(3, 4, Color(128, 128, 128, 128)) {}
 
   base::TimeDelta OverlayScrollbarFadeOutDelay() const override {
     return delay_;

third_party/blink/web_tests/compositing/overflow/reflected-overlay-scrollbars-should-appear-without-compositing-expected.html

@@ -35,19 +35,10 @@ if (window.internals) {
 
 #scrolled {
     width: 100px;
-    height: 300px;
+    height: 400px;
     background: green;
 }
 </style>
-<script>
-if (window.testRunner)
-    testRunner.dumpAsTextWithPixelResults();
-
-onload = function() {
-    if (window.internals && window.testRunner)
-        testRunner.setCustomTextOutput(internals.layerTreeAsText(document));
-};
-</script>
 <div id="container">
   <div id="clipper">
     <div id="scroller">

third_party/blink/web_tests/compositing/overflow/reflected-overlay-scrollbars-should-appear-without-compositing.html

@@ -35,7 +35,7 @@ if (window.internals) {
 
 #scrolled {
     width: 100px;
-    height: 300px;
+    height: 400px;
     background: green;
 }
 </style>

third_party/blink/web_tests/compositing/overflow/reflected-overlay-scrollbars-should-respect-ancestor-clip-expected.html

@@ -36,7 +36,7 @@ if (window.internals) {
 
 #scrolled {
     width: 100px;
-    height: 300px;
+    height: 400px;
     background: green;
 }
 </style>

third_party/blink/web_tests/compositing/overflow/reflected-overlay-scrollbars-should-respect-ancestor-clip.html

@@ -41,7 +41,7 @@ if (window.internals) {
 
 #scrolled {
     width: 100px;
-    height: 300px;
+    height: 400px;
     background: green;
 }
 </style>

third_party/blink/web_tests/fast/forms/select/listbox-overlay-scrollbar-expected.html

@@ -16,7 +16,7 @@ html, body {
     font-size : 12pt;
 }
 .scrollbar {
-    background-color: #808080;
+    background-color: rgba(128, 128, 128, 0.5);
     position: absolute;
 }
 .vertical {
@@ -48,4 +48,4 @@ should have a scrollbar on the left.</p>
 <div class="scrollbar vertical" style="left: 4px; top: 4px;"></div>
 </div>
 </body>
-</html>
\ No newline at end of file
+</html>

third_party/blink/web_tests/fast/scrolling/overlay-scrollbars-expected.html

@@ -13,7 +13,7 @@ html, body {
     position: relative;
 }
 .scrollbar {
-    background-color: #808080;
+    background-color: rgba(128, 128, 128, 0.5);
     position: absolute;
 }
 .horizontal {