use existing capabilityChecker and DuckDuckGoWebView extension

Author: CrisBarreiro

app/src/main/java/com/duckduckgo/app/browser/BrowserTabFragment.kt

@@ -108,6 +108,7 @@ import com.duckduckgo.app.browser.SSLErrorType.NONE
 import com.duckduckgo.app.browser.WebViewErrorResponse.LOADING
 import com.duckduckgo.app.browser.WebViewErrorResponse.OMITTED
 import com.duckduckgo.app.browser.animations.ExperimentTrackersAnimationHelper
+import com.duckduckgo.app.browser.api.DuckDuckGoWebView
 import com.duckduckgo.app.browser.api.WebViewCapabilityChecker
 import com.duckduckgo.app.browser.api.WebViewCapabilityChecker.WebViewCapability
 import com.duckduckgo.app.browser.applinks.AppLinksLauncher
@@ -3206,7 +3207,6 @@ class BrowserTabFragment :
                 WebViewCompat.addDocumentStartJavaScript(webView, script, setOf("*"))
 
                 webView.safeAddWebMessageListener(
-                    webViewCapabilityChecker,
                     "ddgBlobDownloadObj",
                     setOf("*"),
                     object : WebViewCompat.WebMessageListener {

app/src/main/java/com/duckduckgo/app/browser/DuckDuckGoWebView.kt renamed to app/src/main/java/com/duckduckgo/app/browser/RealDuckDuckGoWebView.kt

@@ -33,11 +33,17 @@ import android.webkit.WebViewClient
 import androidx.core.view.NestedScrollingChild3
 import androidx.core.view.NestedScrollingChildHelper
 import androidx.core.view.ViewCompat
+import androidx.webkit.ScriptHandler
 import androidx.webkit.WebViewCompat
 import androidx.webkit.WebViewCompat.WebMessageListener
+import com.duckduckgo.anvil.annotations.InjectWith
+import com.duckduckgo.app.browser.api.DuckDuckGoWebView
 import com.duckduckgo.app.browser.api.WebViewCapabilityChecker
 import com.duckduckgo.app.browser.api.WebViewCapabilityChecker.WebViewCapability
 import com.duckduckgo.app.browser.navigation.safeCopyBackForwardList
+import com.duckduckgo.contentscopescripts.impl.WebViewCompatWrapper
+import com.duckduckgo.di.scopes.ViewScope
+import javax.inject.Inject
 import logcat.LogPriority.ERROR
 import logcat.asLog
 import logcat.logcat
@@ -49,7 +55,9 @@ import logcat.logcat
  *
  * Originally based on https://github.com/takahirom/webview-in-coordinatorlayout for scrolling behaviour
  */
-class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
+
+@InjectWith(ViewScope::class)
+class RealDuckDuckGoWebView : DuckDuckGoWebView, NestedScrollingChild3 {
     private var lastClampedTopY: Boolean = true // when created we are always at the top
     private var contentAllowsSwipeToRefresh: Boolean = true
     private var enableSwipeRefreshCallback: ((Boolean) -> Unit)? = null
@@ -65,7 +73,13 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
     private val helper = CoordinatorLayoutHelper()
 
     private var isDestroyed: Boolean = false
-    var isSafeWebViewEnabled: Boolean = false
+    override var isSafeWebViewEnabled: Boolean = false
+
+    @Inject
+    lateinit var webViewCompatWrapper: WebViewCompatWrapper
+
+    @Inject
+    lateinit var webViewCapabilityChecker: WebViewCapabilityChecker
 
     constructor(context: Context) : this(context, null)
     constructor(
@@ -189,29 +203,29 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
         return super.getUrl()
     }
 
-    fun safeCopyBackForwardList(): WebBackForwardList? {
+    override fun safeCopyBackForwardList(): WebBackForwardList? {
         if (isDestroyed) return null
         return (this as WebView).safeCopyBackForwardList()
     }
 
-    fun createSafePrintDocumentAdapter(documentName: String): PrintDocumentAdapter? {
+    override fun createSafePrintDocumentAdapter(documentName: String): PrintDocumentAdapter? {
         if (isDestroyed) return null
         return createPrintDocumentAdapter(documentName)
     }
 
-    val safeSettings: WebSettings?
+    override val safeSettings: WebSettings?
         get() {
             if (isDestroyed) return null
             return getSettings()
         }
 
-    val safeHitTestResult: HitTestResult?
+    override val safeHitTestResult: HitTestResult?
         get() {
             if (isDestroyed) return null
             return getHitTestResult()
         }
 
-    fun setBottomMatchingBehaviourEnabled(value: Boolean) {
+    override fun setBottomMatchingBehaviourEnabled(value: Boolean) {
         helper.setBottomMatchingBehaviourEnabled(value)
     }
 
@@ -393,11 +407,11 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
         super.onOverScrolled(scrollX, scrollY, clampedX, clampedY)
     }
 
-    fun setEnableSwipeRefreshCallback(callback: (Boolean) -> Unit) {
+    override fun setEnableSwipeRefreshCallback(callback: (Boolean) -> Unit) {
         enableSwipeRefreshCallback = callback
     }
 
-    fun removeEnableSwipeRefreshCallback() {
+    override fun removeEnableSwipeRefreshCallback() {
         enableSwipeRefreshCallback = null
     }
 
@@ -417,8 +431,7 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
     }
 
     @SuppressLint("RequiresFeature", "AddWebMessageListenerUsage")
-    suspend fun safeAddWebMessageListener(
-        webViewCapabilityChecker: WebViewCapabilityChecker,
+    override suspend fun safeAddWebMessageListener(
         jsObjectName: String,
         allowedOriginRules: Set<String>,
         listener: WebMessageListener,
@@ -439,23 +452,18 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
         false
     }
 
-    @SuppressLint("RequiresFeature", "RemoveWebMessageListenerUsage")
-    suspend fun safeRemoveWebMessageListener(
-        webViewCapabilityChecker: WebViewCapabilityChecker,
-        jsObjectName: String,
-    ): Boolean = runCatching {
-        if (webViewCapabilityChecker.isSupported(WebViewCapability.WebMessageListener) && !isDestroyed) {
-            WebViewCompat.removeWebMessageListener(
-                this,
-                jsObjectName,
-            )
-            true
-        } else {
-            false
-        }
-    }.getOrElse { exception ->
-        logcat(ERROR) { "Error removing WebMessageListener: $jsObjectName: ${exception.asLog()}" }
-        false
+    @SuppressLint("RequiresFeature")
+    override suspend fun safeAddDocumentStartJavaScript(
+        script: String,
+        allowedOriginRules: Set<String>,
+    ): ScriptHandler? {
+        return runCatching {
+            if (webViewCapabilityChecker.isSupported(WebViewCapability.DocumentStartJavaScript) && !isDestroyed) {
+                webViewCompatWrapper.addDocumentStartJavaScript(this, script, allowedOriginRules)
+            } else {
+                null
+            }
+        }.getOrElse { null }
     }
 
     companion object {

app/src/main/res/layout/include_duckduckgo_browser_webview.xml

@@ -14,7 +14,7 @@
   ~ limitations under the License.
   -->
 
-<com.duckduckgo.app.browser.DuckDuckGoWebView xmlns:android="http://schemas.android.com/apk/res/android"
+<com.duckduckgo.app.browser.RealDuckDuckGoWebView xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/browserWebView"
@@ -34,4 +34,4 @@
     app:layout_behavior="@string/appbar_scrolling_view_behavior"
     tools:visibility="visible">
 
-</com.duckduckgo.app.browser.DuckDuckGoWebView>
+</com.duckduckgo.app.browser.RealDuckDuckGoWebView>

app/src/test/java/com/duckduckgo/app/browser/RealDuckDuckGoWebViewTest.kt

@@ -0,0 +1,47 @@
+package com.duckduckgo.app.browser
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import com.duckduckgo.app.browser.api.WebViewCapabilityChecker
+import com.duckduckgo.app.browser.api.WebViewCapabilityChecker.WebViewCapability.DocumentStartJavaScript
+import com.duckduckgo.contentscopescripts.impl.WebViewCompatWrapper
+import kotlinx.coroutines.test.runTest
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.Mockito.mock
+import org.mockito.Mockito.verify
+import org.mockito.kotlin.never
+import org.mockito.kotlin.whenever
+
+@RunWith(AndroidJUnit4::class)
+class RealDuckDuckGoWebViewTest {
+
+    val testee: RealDuckDuckGoWebView = RealDuckDuckGoWebView(InstrumentationRegistry.getInstrumentation().targetContext)
+
+    private val mockWebViewCapabilityChecker: WebViewCapabilityChecker = mock()
+    private val mockWebViewCompatWrapper: WebViewCompatWrapper = mock()
+
+    @Before
+    fun setUp() {
+        testee.webViewCompatWrapper = mockWebViewCompatWrapper
+    }
+
+    @Test
+    fun whenSafeAddDocumentStartJavaScriptWithFeatureEnabledThenAddScript() = runTest {
+        whenever(mockWebViewCapabilityChecker.isSupported(DocumentStartJavaScript)).thenReturn(true)
+
+        testee.safeAddDocumentStartJavaScript("script", setOf("*"))
+
+        verify(mockWebViewCompatWrapper).addDocumentStartJavaScript(testee, "script", setOf("*"))
+    }
+
+    @Test
+    fun whenSafeAddDocumentStartJavaScriptWithFeatureDisabledThenDoNotAddScript() = runTest {
+        whenever(mockWebViewCapabilityChecker.isSupported(DocumentStartJavaScript)).thenReturn(false)
+
+        testee.safeAddDocumentStartJavaScript("script", setOf("*"))
+
+        verify(mockWebViewCompatWrapper, never()).addDocumentStartJavaScript(testee, "script", setOf("*"))
+    }
+}

browser-api/build.gradle

@@ -27,6 +27,7 @@ dependencies {
     implementation project(path: ':common-utils')
     implementation project(':feature-toggles-api')
     implementation AndroidX.core.ktx
+    implementation AndroidX.webkit
     implementation KotlinX.coroutines.core
 
     implementation "com.squareup.logcat:logcat:_"

browser-api/src/main/java/com/duckduckgo/app/browser/api/DuckDuckGoWebView.kt

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.app.browser.api
+
+import android.annotation.SuppressLint
+import android.content.Context
+import android.print.PrintDocumentAdapter
+import android.util.AttributeSet
+import android.webkit.WebBackForwardList
+import android.webkit.WebSettings
+import android.webkit.WebView
+import androidx.webkit.ScriptHandler
+import androidx.webkit.WebViewCompat.WebMessageListener
+
+abstract class DuckDuckGoWebView(
+    context: Context,
+    attrs: AttributeSet?,
+) : WebView(context, attrs) {
+    abstract fun removeEnableSwipeRefreshCallback()
+    abstract fun safeCopyBackForwardList(): WebBackForwardList?
+    abstract fun createSafePrintDocumentAdapter(documentName: String): PrintDocumentAdapter?
+    abstract val safeSettings: WebSettings?
+    abstract val safeHitTestResult: HitTestResult?
+    abstract fun setBottomMatchingBehaviourEnabled(value: Boolean)
+    abstract var isSafeWebViewEnabled: Boolean
+    abstract fun setEnableSwipeRefreshCallback(callback: (Boolean) -> Unit)
+
+    @SuppressLint("RequiresFeature", "AddWebMessageListenerUsage")
+    abstract suspend fun safeAddWebMessageListener(
+        jsObjectName: String,
+        allowedOriginRules: Set<String>,
+        listener: WebMessageListener,
+    ): Boolean
+
+    abstract suspend fun safeAddDocumentStartJavaScript(
+        script: String,
+        allowedOriginRules: Set<String>,
+    ): ScriptHandler?
+}

content-scope-scripts/content-scope-scripts-impl/src/main/java/com/duckduckgo/contentscopescripts/impl/ContentScopeScriptsJsInjectorPlugin.kt

@@ -19,6 +19,7 @@ package com.duckduckgo.contentscopescripts.impl
 import android.annotation.SuppressLint
 import android.webkit.WebView
 import androidx.webkit.ScriptHandler
+import com.duckduckgo.app.browser.api.DuckDuckGoWebView
 import com.duckduckgo.browser.api.JsInjectorPlugin
 import com.duckduckgo.common.utils.DispatcherProvider
 import com.duckduckgo.contentscopescripts.api.contentscopeExperiments.ContentScopeExperiments
@@ -34,7 +35,6 @@ class ContentScopeScriptsJsInjectorPlugin @Inject constructor(
     private val adsJsContentScopeScripts: AdsJsContentScopeScripts,
     private val contentScopeExperiments: ContentScopeExperiments,
     private val dispatcherProvider: DispatcherProvider,
-    private val webViewCompatWrapper: WebViewCompatWrapper,
 ) : JsInjectorPlugin {
     private var script: ScriptHandler? = null
     private var currentScriptString: String? = null
@@ -48,9 +48,6 @@ class ContentScopeScriptsJsInjectorPlugin @Inject constructor(
         activeExperiments = withContext(dispatcherProvider.io()) { contentScopeExperiments.getActiveExperiments() }
 
         withContext(dispatcherProvider.main()) {
-            if (!webViewCompatWrapper.isDocumentStartScriptSupported()) {
-                return@withContext
-            }
             val scriptString = adsJsContentScopeScripts.getScript(activeExperiments)
             if (scriptString == currentScriptString) {
                 return@withContext
@@ -60,8 +57,13 @@ class ContentScopeScriptsJsInjectorPlugin @Inject constructor(
                 script = null
             }
             if (adsJsContentScopeScripts.isEnabled()) {
-                currentScriptString = scriptString
-                script = webViewCompatWrapper.addDocumentStartJavaScript(webView, scriptString, setOf("*"))
+                (webView as? DuckDuckGoWebView)?.safeAddDocumentStartJavaScript(
+                    scriptString,
+                    setOf("*"),
+                )?.let {
+                    script = it
+                    currentScriptString = scriptString
+                }
             }
         }
     }

content-scope-scripts/content-scope-scripts-impl/src/main/java/com/duckduckgo/contentscopescripts/impl/RealWebViewCompatWrapper.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 DuckDuckGo
+ * Copyright (c) 2025 DuckDuckGo
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,18 +19,13 @@ package com.duckduckgo.contentscopescripts.impl
 import android.annotation.SuppressLint
 import androidx.webkit.ScriptHandler
 import androidx.webkit.WebViewCompat
-import androidx.webkit.WebViewFeature
 import com.duckduckgo.di.scopes.AppScope
 import com.squareup.anvil.annotations.ContributesBinding
 import javax.inject.Inject
 
 @SuppressLint("RequiresFeature")
 @ContributesBinding(AppScope::class)
 class RealWebViewCompatWrapper @Inject constructor() : WebViewCompatWrapper {
-    override fun isDocumentStartScriptSupported(): Boolean {
-        return WebViewFeature.isFeatureSupported(WebViewFeature.DOCUMENT_START_SCRIPT)
-    }
-
     override fun addDocumentStartJavaScript(
         webView: android.webkit.WebView,
         script: String,

content-scope-scripts/content-scope-scripts-impl/src/main/java/com/duckduckgo/contentscopescripts/impl/WebViewCompatWrapper.kt

@@ -21,8 +21,6 @@ import androidx.webkit.ScriptHandler
 
 interface WebViewCompatWrapper {
 
-    fun isDocumentStartScriptSupported(): Boolean
-
     fun addDocumentStartJavaScript(
         webView: WebView,
         script: String,