[WebLayer] Add Browser.setDarkModeStrategy API.

This CL adds a Browser.setDarkModeStrategy API that allows embedders to
control how WebLayer renders pages when in dark mode. Note that this
doesn't provide a way for embedders to decouple a page's dark mode with
WebLayer's entirely (e.g. render a page in dark mode if WebLayer itself
is in light, or vice versa). This can be added as a separate setting if
we need it in the future.

Bug: 1136653
Change-Id: I0003f1e095fda3280a840cf794619050b48fd581
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2674202
Commit-Queue: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#851359}

weblayer/browser/android/javatests/AndroidManifest_bundle.xml

@@ -15,8 +15,9 @@
        needed when building test cases. -->
   <application>
       <activity android:name="org.chromium.test.broker.OnDeviceInstrumentationBroker"
-          android:exported="true"/>
-      <activity android:name="org.chromium.weblayer.shell.InstrumentationActivity" />
+                android:exported="true"/>
+      <activity android:name="org.chromium.weblayer.shell.InstrumentationActivity"
+                android:theme="@style/Theme.AppCompat.DayNight" />
   </application>
 
   <instrumentation android:name="org.chromium.base.test.BaseChromiumAndroidJUnitRunner"

weblayer/browser/android/javatests/BUILD.gn

@@ -13,6 +13,7 @@ android_library("weblayer_java_tests") {
     "src/org/chromium/weblayer/test/BrowserTest.java",
     "src/org/chromium/weblayer/test/CookieManagerTest.java",
     "src/org/chromium/weblayer/test/CrashReporterTest.java",
+    "src/org/chromium/weblayer/test/DarkModeTest.java",
     "src/org/chromium/weblayer/test/DataClearingTest.java",
     "src/org/chromium/weblayer/test/DisplayCutoutTest.java",
     "src/org/chromium/weblayer/test/DowngradeTest.java",
@@ -54,6 +55,7 @@ android_library("weblayer_java_tests") {
     "//net/android:net_java_test_support",
     "//third_party/android_deps:android_support_v4_java",
     "//third_party/android_deps:androidx_activity_activity_java",
+    "//third_party/android_deps:androidx_appcompat_appcompat_java",
     "//third_party/android_deps:androidx_core_core_java",
     "//third_party/android_deps:androidx_fragment_fragment_java",
     "//third_party/android_deps:androidx_test_runner_java",

weblayer/browser/android/javatests/src/org/chromium/weblayer/test/DarkModeTest.java

@@ -0,0 +1,104 @@
+// Copyright 2021 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.
+
+package org.chromium.weblayer.test;
+
+import android.os.Bundle;
+
+import androidx.appcompat.app.AppCompatDelegate;
+import androidx.test.filters.SmallTest;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.content_public.browser.test.util.TestThreadUtils;
+import org.chromium.weblayer.DarkModeStrategy;
+import org.chromium.weblayer.shell.InstrumentationActivity;
+
+/**
+ * Tests that dark mode is handled correctly.
+ */
+@RunWith(WebLayerJUnit4ClassRunner.class)
+public class DarkModeTest {
+    private InstrumentationActivity mActivity;
+
+    @Rule
+    public InstrumentationActivityTestRule mActivityTestRule =
+            new InstrumentationActivityTestRule();
+
+    private void setDarkModeStrategy(@DarkModeStrategy int darkModeStrategy) {
+        TestThreadUtils.runOnUiThreadBlocking(() -> {
+            mActivity.loadWebLayerSync(mActivityTestRule.getContextForWebLayer());
+            mActivity.getBrowser().setDarkModeStrategy(darkModeStrategy);
+        });
+    }
+
+    private boolean loadPageAndGetPrefersDark() {
+        mActivityTestRule.navigateAndWait(mActivityTestRule.getTestDataURL("dark_mode.html"));
+        return mActivityTestRule.executeScriptAndExtractBoolean(
+                "window.matchMedia('(prefers-color-scheme: dark)').matches");
+    }
+
+    @Test
+    @SmallTest
+    public void testDarkModeWithWebThemeDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.WEB_THEME_DARKENING_ONLY);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertTrue(prefersDark);
+    }
+
+    @Test
+    @SmallTest
+    public void testDarkModeWithUserAgentDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.USER_AGENT_DARKENING_ONLY);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertFalse(prefersDark);
+    }
+
+    @Test
+    @SmallTest
+    public void testDarkModeWithPreferWebThemeDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertTrue(prefersDark);
+    }
+
+    @Test
+    @SmallTest
+    public void testLightModeWithWebThemeDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.WEB_THEME_DARKENING_ONLY);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertFalse(prefersDark);
+    }
+
+    @Test
+    @SmallTest
+    public void testLightModeWithUserAgentDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.USER_AGENT_DARKENING_ONLY);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertFalse(prefersDark);
+    }
+
+    @Test
+    @SmallTest
+    public void testLightModeWithPreferWebThemeDarkening() throws Exception {
+        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
+        mActivity = mActivityTestRule.launchShell(new Bundle());
+        setDarkModeStrategy(DarkModeStrategy.PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING);
+        boolean prefersDark = loadPageAndGetPrefersDark();
+        Assert.assertFalse(prefersDark);
+    }
+}

weblayer/browser/browser_impl.cc

@@ -33,9 +33,7 @@
 #include "base/json/json_writer.h"
 #include "weblayer/browser/browser_process.h"
 #include "weblayer/browser/java/jni/BrowserImpl_jni.h"
-#endif
 
-#if defined(OS_ANDROID)
 using base::android::AttachCurrentThread;
 using base::android::JavaParamRef;
 using base::android::ScopedJavaLocalRef;
@@ -43,6 +41,16 @@ using base::android::ScopedJavaLocalRef;
 
 namespace weblayer {
 
+#if defined(OS_ANDROID)
+// This MUST match the values defined in
+// org.chromium.weblayer_private.interfaces.DarkModeStrategy.
+enum class DarkModeStrategy {
+  kWebThemeDarkeningOnly = 0,
+  kUserAgentDarkeningOnly = 1,
+  kPreferWebThemeOverUserAgentDarkening = 2,
+};
+#endif
+
 // static
 constexpr char BrowserImpl::kPersistenceFilePrefix[];
 
@@ -217,12 +225,41 @@ void BrowserImpl::SetWebPreferences(blink::web_pref::WebPreferences* prefs) {
 #if defined(OS_ANDROID)
   prefs->password_echo_enabled = Java_BrowserImpl_getPasswordEchoEnabled(
       AttachCurrentThread(), java_impl_);
-  prefs->preferred_color_scheme =
-      Java_BrowserImpl_getDarkThemeEnabled(AttachCurrentThread(), java_impl_)
-          ? blink::mojom::PreferredColorScheme::kDark
-          : blink::mojom::PreferredColorScheme::kLight;
   prefs->font_scale_factor =
       Java_BrowserImpl_getFontScale(AttachCurrentThread(), java_impl_);
+  bool is_dark =
+      Java_BrowserImpl_getDarkThemeEnabled(AttachCurrentThread(), java_impl_);
+  if (is_dark) {
+    DarkModeStrategy dark_strategy =
+        static_cast<DarkModeStrategy>(Java_BrowserImpl_getDarkModeStrategy(
+            AttachCurrentThread(), java_impl_));
+    switch (dark_strategy) {
+      case DarkModeStrategy::kPreferWebThemeOverUserAgentDarkening:
+        // Blink's behavior is that if the preferred color scheme matches the
+        // browser's color scheme, then force dark will be disabled, otherwise
+        // the preferred color scheme will be reset to 'light'. Therefore
+        // when enabling force dark, we also set the preferred color scheme to
+        // dark so that dark themed content will be preferred over force
+        // darkening.
+        prefs->preferred_color_scheme =
+            blink::mojom::PreferredColorScheme::kDark;
+        prefs->force_dark_mode_enabled = true;
+        break;
+      case DarkModeStrategy::kWebThemeDarkeningOnly:
+        prefs->preferred_color_scheme =
+            blink::mojom::PreferredColorScheme::kDark;
+        prefs->force_dark_mode_enabled = false;
+        break;
+      case DarkModeStrategy::kUserAgentDarkeningOnly:
+        prefs->preferred_color_scheme =
+            blink::mojom::PreferredColorScheme::kLight;
+        prefs->force_dark_mode_enabled = true;
+        break;
+    }
+  } else {
+    prefs->preferred_color_scheme = blink::mojom::PreferredColorScheme::kLight;
+    prefs->force_dark_mode_enabled = false;
+  }
 #endif
 }
 

weblayer/browser/java/BUILD.gn

@@ -464,6 +464,7 @@ android_library("interfaces_java") {
     "org/chromium/weblayer_private/interfaces/BrowserFragmentArgs.java",
     "org/chromium/weblayer_private/interfaces/BrowsingDataType.java",
     "org/chromium/weblayer_private/interfaces/CookieChangeCause.java",
+    "org/chromium/weblayer_private/interfaces/DarkModeStrategy.java",
     "org/chromium/weblayer_private/interfaces/DownloadError.java",
     "org/chromium/weblayer_private/interfaces/DownloadState.java",
     "org/chromium/weblayer_private/interfaces/GoogleAccountServiceType.java",

weblayer/browser/java/org/chromium/weblayer_private/BrowserImpl.java

@@ -25,6 +25,7 @@ import org.chromium.components.embedder_support.view.ContentView;
 import org.chromium.ui.base.DeviceFormFactor;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.weblayer_private.interfaces.APICallException;
+import org.chromium.weblayer_private.interfaces.DarkModeStrategy;
 import org.chromium.weblayer_private.interfaces.IBrowser;
 import org.chromium.weblayer_private.interfaces.IBrowserClient;
 import org.chromium.weblayer_private.interfaces.IObjectWrapper;
@@ -83,6 +84,8 @@ public class BrowserImpl extends IBrowser.Stub implements View.OnAttachStateChan
     // Cache the value instead of querying system every time.
     private Boolean mPasswordEchoEnabled;
     private Boolean mDarkThemeEnabled;
+    @DarkModeStrategy
+    private int mDarkModeStrategy = DarkModeStrategy.WEB_THEME_DARKENING_ONLY;
     private Float mFontScale;
     private boolean mViewAttachedToWindow;
     private boolean mNotifyOnBrowserControlsOffsetsChanged;
@@ -479,6 +482,20 @@ public class BrowserImpl extends IBrowser.Stub implements View.OnAttachStateChan
         tab.destroy();
     }
 
+    @Override
+    public void setDarkModeStrategy(@DarkModeStrategy int strategy) {
+        if (mDarkModeStrategy == strategy) {
+            return;
+        }
+        mDarkModeStrategy = strategy;
+        BrowserImplJni.get().webPreferencesChanged(mNativeBrowser);
+    }
+
+    @CalledByNative
+    int getDarkModeStrategy() {
+        return mDarkModeStrategy;
+    }
+
     @Override
     public IUrlBarController getUrlBarController() {
         StrictModeWorkaround.apply();

weblayer/browser/java/org/chromium/weblayer_private/interfaces/DarkModeStrategy.java

@@ -0,0 +1,19 @@
+// Copyright 2021 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.
+
+package org.chromium.weblayer_private.interfaces;
+
+import androidx.annotation.IntDef;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@IntDef({DarkModeStrategy.PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING,
+        DarkModeStrategy.WEB_THEME_DARKENING_ONLY, DarkModeStrategy.USER_AGENT_DARKENING_ONLY})
+@Retention(RetentionPolicy.SOURCE)
+public @interface DarkModeStrategy {
+    int WEB_THEME_DARKENING_ONLY = 0;
+    int USER_AGENT_DARKENING_ONLY = 1;
+    int PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING = 2;
+}

weblayer/browser/java/org/chromium/weblayer_private/interfaces/IBrowser.aidl

@@ -48,4 +48,7 @@ interface IBrowser {
 
   // Added in 89.
   void setMinimumSurfaceSize(in int width, in int height) = 15;
+
+  // Added in 90.
+  void setDarkModeStrategy(in int strategy) = 16;
 }

weblayer/public/java/BUILD.gn

@@ -52,6 +52,7 @@ android_library("java") {
     "org/chromium/weblayer/CookieManager.java",
     "org/chromium/weblayer/CrashReporterCallback.java",
     "org/chromium/weblayer/CrashReporterController.java",
+    "org/chromium/weblayer/DarkModeStrategy.java",
     "org/chromium/weblayer/Download.java",
     "org/chromium/weblayer/DownloadCallback.java",
     "org/chromium/weblayer/DownloadError.java",

weblayer/public/java/org/chromium/weblayer/Browser.java

@@ -432,6 +432,31 @@ public class Browser {
         }
     }
 
+    /**
+     * Controls how sites are themed when WebLayer is in dark mode. WebLayer considers itself to be
+     * in dark mode if the UI_MODE_NIGHT_YES flag of its Resources' Configuration's uiMode field is
+     * set, which is typically controlled with AppCompatDelegate#setDefaultNightMode. By default
+     * pages will only be rendered in dark mode if WebLayer is in dark mode and they provide a dark
+     * theme in CSS. See DarkModeStrategy for other possible configurations.
+     *
+     * @see DarkModeStrategy
+     * @param strategy See {@link DarkModeStrategy}.
+     *
+     * @since 90
+     */
+    public void setDarkModeStrategy(@DarkModeStrategy int strategy) {
+        ThreadCheck.ensureOnUiThread();
+        if (WebLayer.getSupportedMajorVersionInternal() < 89) {
+            throw new UnsupportedOperationException();
+        }
+        throwIfDestroyed();
+        try {
+            mImpl.setDarkModeStrategy(strategy);
+        } catch (RemoteException e) {
+            throw new APICallException(e);
+        }
+    }
+
     /**
      * Returns {@link Profile} associated with this Browser Fragment. Multiple fragments can share
      * the same Profile.

weblayer/public/java/org/chromium/weblayer/DarkModeStrategy.java

@@ -0,0 +1,40 @@
+// Copyright 2021 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.
+
+package org.chromium.weblayer;
+
+import androidx.annotation.IntDef;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * @hide
+ */
+@IntDef({DarkModeStrategy.PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING,
+        DarkModeStrategy.WEB_THEME_DARKENING_ONLY, DarkModeStrategy.USER_AGENT_DARKENING_ONLY})
+@Retention(RetentionPolicy.SOURCE)
+public @interface DarkModeStrategy {
+    /**
+     * Only render pages in dark mode if they provide a dark theme in their CSS. If no theme is
+     * provided, the page will render with its default styling, which could be a light theme.
+     */
+    int WEB_THEME_DARKENING_ONLY =
+            org.chromium.weblayer_private.interfaces.DarkModeStrategy.WEB_THEME_DARKENING_ONLY;
+
+    /**
+     * Always apply automatic user-agent darkening to pages, ignoring any dark theme that the
+     * site provides. All pages will appear dark in this mode.
+     */
+    int USER_AGENT_DARKENING_ONLY =
+            org.chromium.weblayer_private.interfaces.DarkModeStrategy.USER_AGENT_DARKENING_ONLY;
+
+    /**
+     * Render pages using their specified dark theme if available, otherwise fall back on automatic
+     * user-agent darkening. All pages will appear dark in this mode.
+     */
+    int PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING =
+            org.chromium.weblayer_private.interfaces.DarkModeStrategy
+                    .PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING;
+}

weblayer/shell/android/shell_apk/AndroidManifest.xml

@@ -29,6 +29,7 @@
             </intent-filter>
         </activity>
         <activity android:name="InstrumentationActivity"
+                  android:theme="@style/Theme.AppCompat.DayNight"
                   android:windowSoftInputMode="adjustResize">
             <!-- Add these intent filters so tests can resolve these intents. -->
             <intent-filter>

weblayer/shell/android/shell_apk/res/menu/controls_menu.xml

@@ -24,7 +24,21 @@
     <item android:id="@+id/toggle_controls_animations_id"
         android:checkable="true"
         android:title="Animate browser controls changes" />
-    <item android:id="@+id/toggle_dark_mode"
-        android:checkable="true"
-        android:title="Dark Mode" />
+    <item android:title="Dark Mode">
+        <menu>
+            <item android:id="@+id/toggle_dark_mode"
+                  android:checkable="true"
+                  android:title="Enable dark mode" />
+            <item android:enabled="false"
+                  android:title="Dark mode strategy" />
+            <group android:checkableBehavior="single">
+                <item android:id="@+id/dark_mode_web_theme"
+                      android:title="Web theme only" />
+                <item android:id="@+id/dark_mode_user_agent"
+                      android:title="User agent only" />
+                <item android:id="@+id/dark_mode_prefer_web_theme"
+                      android:title="Prefer web theme" />
+            </group>
+        </menu>
+    </item>
 </menu>

weblayer/shell/android/shell_apk/src/org/chromium/weblayer/shell/InstrumentationActivity.java

@@ -18,8 +18,8 @@ import android.view.WindowManager;
 import android.widget.LinearLayout;
 import android.widget.RelativeLayout;
 
+import androidx.appcompat.app.AppCompatActivity;
 import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentActivity;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentTransaction;
 
@@ -46,7 +46,7 @@ import java.util.List;
  */
 // This isn't part of Chrome, so using explicit colors/sizes is ok.
 @SuppressWarnings("checkstyle:SetTextColorAndSetTextSizeCheck")
-public class InstrumentationActivity extends FragmentActivity {
+public class InstrumentationActivity extends AppCompatActivity {
     private static final String TAG = "WLInstrumentation";
     private static final String KEY_MAIN_VIEW_ID = "mainViewId";
 

weblayer/shell/android/shell_apk/src/org/chromium/weblayer/shell/WebLayerShellActivity.java

@@ -52,6 +52,7 @@ import org.chromium.base.compat.ApiHelperForR;
 import org.chromium.weblayer.Browser;
 import org.chromium.weblayer.BrowsingDataType;
 import org.chromium.weblayer.ContextMenuParams;
+import org.chromium.weblayer.DarkModeStrategy;
 import org.chromium.weblayer.ErrorPageCallback;
 import org.chromium.weblayer.FaviconCallback;
 import org.chromium.weblayer.FaviconFetcher;
@@ -257,6 +258,7 @@ public class WebLayerShellActivity extends AppCompatActivity {
     private boolean mSetDarkMode;
     private boolean mInIncognitoMode;
     private boolean mEnableAltTopView;
+    private int mDarkModeStrategy = R.id.dark_mode_web_theme;
 
     @Override
     protected void onCreate(final Bundle savedInstanceState) {
@@ -406,6 +408,7 @@ public class WebLayerShellActivity extends AppCompatActivity {
                 .findItem(R.id.toggle_controls_animations_id)
                 .setChecked(mAnimateControlsChanges);
         popup.getMenu().findItem(R.id.toggle_dark_mode).setChecked(mSetDarkMode);
+        popup.getMenu().findItem(mDarkModeStrategy).setChecked(true);
 
         popup.setOnMenuItemClickListener(item -> {
             if (item.getItemId() == R.id.toggle_top_view_id) {
@@ -454,6 +457,25 @@ public class WebLayerShellActivity extends AppCompatActivity {
                 return true;
             }
 
+            if (item.getItemId() == R.id.dark_mode_web_theme) {
+                mDarkModeStrategy = R.id.dark_mode_web_theme;
+                mBrowser.setDarkModeStrategy(DarkModeStrategy.WEB_THEME_DARKENING_ONLY);
+                return true;
+            }
+
+            if (item.getItemId() == R.id.dark_mode_user_agent) {
+                mDarkModeStrategy = R.id.dark_mode_user_agent;
+                mBrowser.setDarkModeStrategy(DarkModeStrategy.USER_AGENT_DARKENING_ONLY);
+                return true;
+            }
+
+            if (item.getItemId() == R.id.dark_mode_prefer_web_theme) {
+                mDarkModeStrategy = R.id.dark_mode_prefer_web_theme;
+                mBrowser.setDarkModeStrategy(
+                        DarkModeStrategy.PREFER_WEB_THEME_OVER_USER_AGENT_DARKENING);
+                return true;
+            }
+
             return false;
         });
         popup.show();

weblayer/test/data/dark_mode.html

@@ -0,0 +1,6 @@
+<html>
+  <head>
+    <meta name="color-scheme" content="dark light">
+  </head>
+  <body></body>
+</html>