Add support to unregister message listener

Author: CrisBarreiro

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

@@ -3855,8 +3855,13 @@ class BrowserTabFragment :
 
     private fun destroyWebView() {
         if (::webViewContainer.isInitialized) webViewContainer.removeAllViews()
-        webView?.destroy()
-        webView = null
+        appCoroutineScope.launch(dispatchers.main()) {
+            webView?.let {
+                adsJsContentScopeScripts.unregister(it)
+                it.destroy()
+            }
+            webView = null
+        }
     }
 
     private fun convertBlobToDataUri(blob: Command.ConvertBlobToDataUri) {

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

@@ -18,6 +18,7 @@ package com.duckduckgo.contentscopescripts.impl
 
 import com.duckduckgo.app.privacy.db.UserAllowListRepository
 import com.duckduckgo.appbuildconfig.api.AppBuildConfig
+import com.duckduckgo.common.utils.DispatcherProvider
 import com.duckduckgo.common.utils.plugins.PluginPoint
 import com.duckduckgo.contentscopescripts.api.ContentScopeConfigPlugin
 import com.duckduckgo.di.scopes.AppScope
@@ -35,6 +36,7 @@ import java.util.concurrent.CopyOnWriteArrayList
 import javax.inject.Inject
 import javax.inject.Named
 import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withContext
 
 interface AdsJsContentScopeScripts {
     fun getScript(
@@ -58,6 +60,7 @@ class RealAdsJsContentScopeScripts @Inject constructor(
     private val unprotectedTemporary: UnprotectedTemporary,
     private val fingerprintProtectionManager: FingerprintProtectionManager,
     private val contentScopeScriptsFeature: ContentScopeScriptsFeature,
+    private val dispatcherProvider: DispatcherProvider,
 ) : AdsJsContentScopeScripts {
 
     private var cachedContentScopeJson: String = getContentScopeJson("", emptyList())
@@ -112,7 +115,9 @@ class RealAdsJsContentScopeScripts @Inject constructor(
     }
 
     override suspend fun isEnabled(): Boolean {
-        return contentScopeScriptsFeature.self().isEnabled() && contentScopeScriptsFeature.useNewWebCompatApis().isEnabled()
+        return withContext(dispatcherProvider.io()) {
+            contentScopeScriptsFeature.self().isEnabled() && contentScopeScriptsFeature.useNewWebCompatApis().isEnabled()
+        }
     }
 
     private fun getSecretKeyValuePair() = "\"messageSecret\":\"$secret\""

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

@@ -38,6 +38,8 @@ import logcat.LogPriority.ERROR
 import logcat.asLog
 import logcat.logcat
 
+private const val JS_OBJECT_NAME = "contentScopeAdsjs"
+
 @ContributesBinding(ActivityScope::class)
 @Named("AdsjsContentScopeScripts")
 class AdsjsContentScopeMessaging @Inject constructor(
@@ -93,7 +95,7 @@ class AdsjsContentScopeMessaging @Inject constructor(
             if (WebViewFeature.isFeatureSupported(WebViewFeature.WEB_MESSAGE_LISTENER)) {
                 WebViewCompat.addWebMessageListener(
                     webView,
-                    "contentScopeAdsjs",
+                    JS_OBJECT_NAME,
                     allowedDomains,
                 ) { _, message, _, _, replyProxy ->
                     process(
@@ -110,4 +112,17 @@ class AdsjsContentScopeMessaging @Inject constructor(
             false
         }
     }
+
+    override suspend fun unregister(webView: WebView) {
+        if (!adsJsContentScopeScripts.isEnabled()) return
+        withContext(dispatcherProvider.main()) {
+            runCatching {
+                if (WebViewFeature.isFeatureSupported(WebViewFeature.WEB_MESSAGE_LISTENER)) {
+                    WebViewCompat.removeWebMessageListener(webView, JS_OBJECT_NAME)
+                } else {
+                    logcat(ERROR) { "WebMessageListener is not supported on this WebView" }
+                }
+            }
+        }
+    }
 }

js-messaging/js-messaging-api/src/main/java/com/duckduckgo/js/messaging/api/AdsjsMessaging.kt

@@ -24,6 +24,7 @@ interface AdsjsMessaging {
      * Method to register the JS interface to the webView instance
      */
     suspend fun register(webView: WebView, jsMessageCallback: JsMessageCallback?)
+    suspend fun unregister(webView: WebView)
 
     /**
      * Context name