Add a middle preference between LCD text and compositing

When the middle preference (LCDTextPreference::kGoodToHave) is used,
we will still prefer composited scrolling, but will try to preserve
LCD text when possible. In production, the preference comes from
WidgetBase::ComputeLCDTextPreference() (previous
ComputePreferCompositingToLCDText()).

For now the new preference value is the same as kIgnored and is not
used. It will be used in an experiment to pull solid opaque background
color from underlying layers to enable LCD text in layers with
transparent backgrounds.

In most tests the new value will be always the same as kIgnored, so
we keep Settings::SetPreferCompositingToLCDTextForTesting().

Bug: 1353921
Change-Id: I5ae4dc059f6ba99dd074272ff3eb44e88fd93938
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4337728
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1117778}

third_party/blink/common/features.cc

@@ -859,7 +859,14 @@ const base::FeatureParam<CheckOfflineCapabilityMode>
 // means losing lcd text.
 BASE_FEATURE(kPreferCompositingToLCDText,
              "PreferCompositingToLCDText",
-             base::FEATURE_DISABLED_BY_DEFAULT);
+// On Android we never have LCD text. On Chrome OS we prefer composited
+// scrolling for better scrolling performance.
+#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_CHROMEOS)
+             base::FEATURE_ENABLED_BY_DEFAULT
+#else
+             base::FEATURE_DISABLED_BY_DEFAULT
+#endif
+);
 
 BASE_FEATURE(kLogUnexpectedIPCPostedToBackForwardCachedDocuments,
              "LogUnexpectedIPCPostedToBackForwardCachedDocuments",

third_party/blink/public/web/web_settings.h

@@ -42,6 +42,7 @@
 
 namespace blink {
 
+enum class LCDTextPreference;
 class WebString;
 
 // WebSettings is owned by the WebView and allows code to modify the settings
@@ -91,7 +92,7 @@ class WebSettings {
   virtual bool ShrinksViewportContentToFit() const = 0;
   virtual bool ViewportEnabled() const = 0;
   virtual void SetAccelerated2dCanvasMSAASampleCount(int) = 0;
-  virtual void SetPreferCompositingToLCDTextEnabled(bool) = 0;
+  virtual void SetLCDTextPreference(LCDTextPreference) = 0;
   // Not implemented yet, see http://crbug.com/178119
   virtual void SetAcceleratedCompositingForTransitionEnabled(bool) {}
   // If set to true, allows frames with an https origin to display passive

third_party/blink/renderer/core/animation/animation_test.cc

@@ -2256,7 +2256,7 @@ TEST_P(AnimationPendingAnimationsTest,
 
 TEST_P(AnimationAnimationTestCompositing,
        ScrollLinkedAnimationNotCompositedIfSourceIsNotComposited) {
-  GetDocument().GetSettings()->SetPreferCompositingToLCDTextEnabled(false);
+  SetPreferCompositingToLCDText(false);
   SetBodyInnerHTML(R"HTML(
     <style>
       #scroller { overflow: scroll; width: 100px; height: 100px; }

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

@@ -486,8 +486,8 @@ void WebSettingsImpl::SetAntialiasedClips2dCanvasEnabled(bool enabled) {
   settings_->SetAntialiasedClips2dCanvasEnabled(enabled);
 }
 
-void WebSettingsImpl::SetPreferCompositingToLCDTextEnabled(bool enabled) {
-  dev_tools_emulator_->SetPreferCompositingToLCDTextEnabled(enabled);
+void WebSettingsImpl::SetLCDTextPreference(LCDTextPreference preference) {
+  dev_tools_emulator_->SetLCDTextPreference(preference);
 }
 
 void WebSettingsImpl::SetHideDownloadUI(bool hide) {

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

@@ -53,7 +53,7 @@ class CORE_EXPORT WebSettingsImpl final : public WebSettings {
   bool ViewportEnabled() const override;
   void SetAccelerated2dCanvasMSAASampleCount(int) override;
   void SetAutoplayPolicy(mojom::blink::AutoplayPolicy) override;
-  void SetPreferCompositingToLCDTextEnabled(bool) override;
+  void SetLCDTextPreference(LCDTextPreference) override;
   void SetAccessibilityPasswordValuesEnabled(bool) override;
   void SetAllowFileAccessFromFileURLs(bool) override;
   void SetAllowCustomScrollbarInMainFrame(bool) override;

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

@@ -3656,14 +3656,12 @@ TEST_F(MiddleClickWebViewTest, MiddleClickAutoscrollCursor) {
   web_view_helper_.Reset();
 }
 
-static void ConfigueCompositingWebView(WebSettings* settings) {
-  settings->SetPreferCompositingToLCDTextEnabled(true);
-}
-
 TEST_F(WebViewTest, ShowPressOnTransformedLink) {
   frame_test_helpers::WebViewHelper web_view_helper;
-  WebViewImpl* web_view_impl =
-      web_view_helper.InitializeWithSettings(&ConfigueCompositingWebView);
+  WebViewImpl* web_view_impl = web_view_helper.Initialize();
+  web_view_impl->GetPage()
+      ->GetSettings()
+      .SetPreferCompositingToLCDTextForTesting(true);
 
   int page_width = 640;
   int page_height = 480;

third_party/blink/renderer/core/frame/browser_controls_test.cc

@@ -104,12 +104,8 @@ class BrowserControlsTest : public testing::Test,
 
   static void ConfigureSettings(WebSettings* settings) {
     settings->SetJavaScriptEnabled(true);
-    settings->SetPreferCompositingToLCDTextEnabled(true);
-    // Android settings
-    settings->SetViewportEnabled(true);
-    settings->SetViewportMetaEnabled(true);
-    settings->SetShrinksViewportContentToFit(true);
-    settings->SetMainFrameResizesAreOrientationChanges(true);
+    frame_test_helpers::WebViewHelper::UpdateAndroidCompositingSettings(
+        settings);
   }
 
   void RegisterMockedHttpURLLoad(const std::string& file_name) {
@@ -196,14 +192,8 @@ class BrowserControlsSimTest : public SimTest {
 
   void SetUp() override {
     SimTest::SetUp();
-
-    // Use settings that resemble the Android configuration.
-    WebView().GetSettings()->SetViewportEnabled(true);
-    WebView().GetSettings()->SetPreferCompositingToLCDTextEnabled(true);
-    WebView().GetSettings()->SetViewportMetaEnabled(true);
-    WebView().GetSettings()->SetViewportEnabled(true);
-    WebView().GetSettings()->SetMainFrameResizesAreOrientationChanges(true);
-    WebView().GetSettings()->SetShrinksViewportContentToFit(true);
+    frame_test_helpers::WebViewHelper::UpdateAndroidCompositingSettings(
+        WebView().GetSettings());
     WebView().SetDefaultPageScaleLimits(0.25f, 5);
     Compositor().LayerTreeHost()->UpdateBrowserControlsState(
         cc::BrowserControlsState::kBoth, cc::BrowserControlsState::kShown,

third_party/blink/renderer/core/frame/frame_test_helpers.cc

@@ -474,6 +474,15 @@ WebViewImpl* WebViewHelper::InitializeWithSettings(
   return InitializeWithOpener(nullptr, nullptr, nullptr, update_settings_func);
 }
 
+// static
+void WebViewHelper::UpdateAndroidCompositingSettings(WebSettings* settings) {
+  settings->SetLCDTextPreference(LCDTextPreference::kIgnored);
+  settings->SetViewportMetaEnabled(true);
+  settings->SetViewportEnabled(true);
+  settings->SetMainFrameResizesAreOrientationChanges(true);
+  settings->SetShrinksViewportContentToFit(true);
+}
+
 WebViewImpl* WebViewHelper::InitializeAndLoad(
     const std::string& url,
     TestWebFrameClient* web_frame_client,

third_party/blink/renderer/core/frame/frame_test_helpers.h

@@ -352,6 +352,11 @@ class WebViewHelper : public ScopedMockOverlayScrollbars {
   WebViewImpl* InitializeWithSettings(
       void (*update_settings_func)(WebSettings*));
 
+  WebViewImpl* InitializeWithAndroidSettings() {
+    return InitializeWithSettings(&UpdateAndroidCompositingSettings);
+  }
+  static void UpdateAndroidCompositingSettings(WebSettings*);
+
   // Same as Initialize() but also performs the initial load of the url. Only
   // returns once the load is complete.
   WebViewImpl* InitializeAndLoad(

third_party/blink/renderer/core/frame/local_frame_view.cc

@@ -3037,8 +3037,8 @@ void LocalFrameView::PushPaintArtifactToCompositor(bool repainted) {
         paint_artifact_compositor_->RootLayer(), &GetFrame());
   }
 
-  paint_artifact_compositor_->SetPrefersLCDText(
-      !page->GetSettings().GetPreferCompositingToLCDTextEnabled());
+  paint_artifact_compositor_->SetLCDTextPreference(
+      page->GetSettings().GetLCDTextPreference());
 
   SCOPED_UMA_AND_UKM_TIMER(GetUkmAggregator(),
                            LocalFrameUkmAggregator::kCompositingCommit);

third_party/blink/renderer/core/frame/local_frame_view_test.cc

@@ -208,8 +208,7 @@ TEST_F(LocalFrameViewTest, CanHaveScrollbarsIfScrollingAttrEqualsNoChanged) {
 
 TEST_F(LocalFrameViewTest,
        MainThreadScrollingForBackgroundFixedAttachmentWithCompositing) {
-  GetDocument().GetFrame()->GetSettings()->SetPreferCompositingToLCDTextEnabled(
-      true);
+  SetPreferCompositingToLCDText(true);
 
   SetBodyInnerHTML(R"HTML(
     <style>

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

@@ -118,4 +118,9 @@ void Settings::Invalidate(SettingsDelegate::ChangeType change_type) {
     delegate_->SettingsChanged(change_type);
 }
 
+void Settings::SetPreferCompositingToLCDTextForTesting(bool enabled) {
+  SetLCDTextPreference(enabled ? LCDTextPreference::kIgnored
+                               : LCDTextPreference::kStronglyPreferred);
+}
+
 }  // namespace blink

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

@@ -43,6 +43,7 @@
 #include "third_party/blink/renderer/core/loader/frame_loader_types.h"
 #include "third_party/blink/renderer/core/settings_macros.h"
 #include "third_party/blink/renderer/platform/fonts/generic_font_family_settings.h"
+#include "third_party/blink/renderer/platform/graphics/lcd_text_preference.h"
 #include "third_party/blink/renderer/platform/timer.h"
 #include "third_party/blink/renderer/platform/weborigin/kurl.h"
 #include "ui/base/pointer/pointer_device.h"
@@ -67,6 +68,8 @@ class CORE_EXPORT Settings {
 
   SETTINGS_GETTERS_AND_SETTERS
 
+  void SetPreferCompositingToLCDTextForTesting(bool enabled);
+
   void SetDelegate(SettingsDelegate*);
 
  private:

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

@@ -165,8 +165,9 @@
     },
 
     {
-      name: "preferCompositingToLCDTextEnabled",
-      initial: false,
+      name: "LCDTextPreference",
+      type: "LCDTextPreference",
+      initial: "LCDTextPreference::kStronglyPreferred",
       invalidate: ["AcceleratedCompositing"],
     },
 

third_party/blink/renderer/core/frame/visual_viewport_test.cc

@@ -78,14 +78,6 @@ ::std::ostream& operator<<(::std::ostream& os, const ContextMenuData& data) {
 
 namespace {
 
-void ConfigureAndroidCompositing(WebSettings* settings) {
-  settings->SetPreferCompositingToLCDTextEnabled(true);
-  settings->SetViewportMetaEnabled(true);
-  settings->SetViewportEnabled(true);
-  settings->SetMainFrameResizesAreOrientationChanges(true);
-  settings->SetShrinksViewportContentToFit(true);
-}
-
 const cc::EffectNode* GetEffectNode(const cc::Layer* layer) {
   return layer->layer_tree_host()->property_trees()->effect_tree().Node(
       layer->effect_tree_index());
@@ -96,19 +88,16 @@ class VisualViewportTest : public testing::Test,
  public:
   VisualViewportTest() : base_url_("http://www.test.com/") {}
 
-  void InitializeWithDesktopSettings(
-      void (*override_settings_func)(WebSettings*) = nullptr) {
-    if (!override_settings_func)
-      override_settings_func = &ConfigureSettings;
-    helper_.Initialize(nullptr, nullptr, override_settings_func);
+  void InitializeWithDesktopSettings() {
+    helper_.InitializeWithSettings(&ConfigureSettings);
     WebView()->SetDefaultPageScaleLimits(1, 4);
   }
 
   void InitializeWithAndroidSettings(
       void (*override_settings_func)(WebSettings*) = nullptr) {
     if (!override_settings_func)
       override_settings_func = &ConfigureAndroidSettings;
-    helper_.Initialize(nullptr, nullptr, override_settings_func);
+    helper_.InitializeWithSettings(override_settings_func);
     WebView()->SetDefaultPageScaleLimits(0.25f, 5);
   }
 
@@ -159,15 +148,13 @@ class VisualViewportTest : public testing::Test,
 
   static void ConfigureSettings(WebSettings* settings) {
     settings->SetJavaScriptEnabled(true);
-    settings->SetPreferCompositingToLCDTextEnabled(true);
+    settings->SetLCDTextPreference(LCDTextPreference::kIgnored);
   }
 
   static void ConfigureAndroidSettings(WebSettings* settings) {
     ConfigureSettings(settings);
-    settings->SetViewportEnabled(true);
-    settings->SetViewportMetaEnabled(true);
-    settings->SetShrinksViewportContentToFit(true);
-    settings->SetMainFrameResizesAreOrientationChanges(true);
+    frame_test_helpers::WebViewHelper::UpdateAndroidCompositingSettings(
+        settings);
   }
 
   const DisplayItemClient& ScrollingBackgroundClient(const Document* document) {
@@ -1592,7 +1579,7 @@ TEST_P(VisualViewportTest, TestTopControlHidingResizeDoesntClampMainFrame) {
   EXPECT_EQ(500, frame_view.LayoutViewport()->GetScrollOffset().y());
 }
 
-static void configureHiddenScrollbarsSettings(WebSettings* settings) {
+static void ConfigureHiddenScrollbarsSettings(WebSettings* settings) {
   VisualViewportTest::ConfigureAndroidSettings(settings);
   settings->SetHideScrollbars(true);
 }
@@ -1601,7 +1588,7 @@ static void configureHiddenScrollbarsSettings(WebSettings* settings) {
 // layer when hideScrollbars WebSetting is true.
 TEST_P(VisualViewportTest,
        TestScrollbarsNotAttachedWhenHideScrollbarsSettingIsTrue) {
-  InitializeWithAndroidSettings(configureHiddenScrollbarsSettings);
+  InitializeWithAndroidSettings(ConfigureHiddenScrollbarsSettings);
   WebView()->MainFrameViewWidget()->Resize(gfx::Size(100, 150));
   NavigateTo("about:blank");
 
@@ -1703,8 +1690,7 @@ TEST_P(VisualViewportTest, ElementBoundsInWidgetSpaceAccountsForViewport) {
 // Test that the various window.scroll and document.body.scroll properties and
 // methods don't change with the visual viewport.
 TEST_P(VisualViewportTest, visualViewportIsInert) {
-  WebViewImpl* web_view_impl =
-      helper_.InitializeWithSettings(&ConfigureAndroidCompositing);
+  WebViewImpl* web_view_impl = helper_.InitializeWithAndroidSettings();
 
   web_view_impl->MainFrameViewWidget()->Resize(gfx::Size(200, 300));
 
@@ -2023,8 +2009,7 @@ TEST_P(VisualViewportTest, ResizeWithScrollAnchoring) {
 // Make sure a composited background-attachment:fixed background gets resized
 // by browser controls.
 TEST_P(VisualViewportTest, ResizeCompositedAndFixedBackground) {
-  WebViewImpl* web_view_impl =
-      helper_.InitializeWithSettings(&ConfigureAndroidCompositing);
+  WebViewImpl* web_view_impl = helper_.InitializeWithAndroidSettings();
 
   int page_width = 640;
   int page_height = 480;
@@ -2085,19 +2070,16 @@ TEST_P(VisualViewportTest, ResizeCompositedAndFixedBackground) {
   EXPECT_EQ(page_height, background_layer->bounds().height());
 }
 
-static void ConfigureAndroidNonCompositing(WebSettings* settings) {
-  settings->SetPreferCompositingToLCDTextEnabled(false);
-  settings->SetViewportMetaEnabled(true);
-  settings->SetViewportEnabled(true);
-  settings->SetMainFrameResizesAreOrientationChanges(true);
-  settings->SetShrinksViewportContentToFit(true);
+static void ConfigureViewportNonCompositing(WebSettings* settings) {
+  frame_test_helpers::WebViewHelper::UpdateAndroidCompositingSettings(settings);
+  settings->SetLCDTextPreference(LCDTextPreference::kStronglyPreferred);
 }
 
 // Make sure a non-composited background-attachment:fixed background gets
 // resized by browser controls.
 TEST_P(VisualViewportTest, ResizeNonCompositedAndFixedBackground) {
   WebViewImpl* web_view_impl =
-      helper_.InitializeWithSettings(&ConfigureAndroidNonCompositing);
+      helper_.InitializeWithSettings(&ConfigureViewportNonCompositing);
 
   int page_width = 640;
   int page_height = 480;
@@ -2173,8 +2155,7 @@ TEST_P(VisualViewportTest, ResizeNonCompositedAndFixedBackground) {
 // Make sure a browser control resize with background-attachment:not-fixed
 // background doesn't cause invalidation or layout.
 TEST_P(VisualViewportTest, ResizeNonFixedBackgroundNoLayoutOrInvalidation) {
-  WebViewImpl* web_view_impl =
-      helper_.InitializeWithSettings(&ConfigureAndroidCompositing);
+  WebViewImpl* web_view_impl = helper_.InitializeWithAndroidSettings();
 
   int page_width = 640;
   int page_height = 480;
@@ -2234,8 +2215,7 @@ TEST_P(VisualViewportTest, ResizeNonFixedBackgroundNoLayoutOrInvalidation) {
 }
 
 TEST_P(VisualViewportTest, InvalidateLayoutViewWhenDocumentSmallerThanView) {
-  WebViewImpl* web_view_impl =
-      helper_.InitializeWithSettings(&ConfigureAndroidCompositing);
+  WebViewImpl* web_view_impl = helper_.InitializeWithAndroidSettings();
 
   int page_width = 320;
   int page_height = 590;
@@ -2423,14 +2403,8 @@ class VisualViewportSimTest : public SimTest {
 
   void SetUp() override {
     SimTest::SetUp();
-
-    // Use settings that resemble the Android configuration.
-    WebView().GetSettings()->SetViewportEnabled(true);
-    WebView().GetSettings()->SetPreferCompositingToLCDTextEnabled(true);
-    WebView().GetSettings()->SetViewportMetaEnabled(true);
-    WebView().GetSettings()->SetViewportEnabled(true);
-    WebView().GetSettings()->SetMainFrameResizesAreOrientationChanges(true);
-    WebView().GetSettings()->SetShrinksViewportContentToFit(true);
+    frame_test_helpers::WebViewHelper::UpdateAndroidCompositingSettings(
+        WebView().GetSettings());
     WebView().SetDefaultPageScaleLimits(0.25f, 5);
   }
 };