Add isDestroyed guard to WebView methods (#4787)

Task/Issue URL:
https://app.asana.com/0/1200204095367872/1207860204325574/f

### Description
This task adds `isDestroyed` checks to all the `WebView` methods used in
`DuckDuckGoWebView`.

### Steps to test this PR
- [ ] Smoke test

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

@@ -122,7 +122,6 @@ import com.duckduckgo.app.browser.menu.BrowserPopupMenu
 import com.duckduckgo.app.browser.model.BasicAuthenticationCredentials
 import com.duckduckgo.app.browser.model.BasicAuthenticationRequest
 import com.duckduckgo.app.browser.model.LongPressTarget
-import com.duckduckgo.app.browser.navigation.safeCopyBackForwardList
 import com.duckduckgo.app.browser.newtab.FocusedViewProvider
 import com.duckduckgo.app.browser.newtab.NewTabPageProvider
 import com.duckduckgo.app.browser.omnibar.OmnibarScrolling
@@ -156,6 +155,7 @@ import com.duckduckgo.app.browser.viewstate.SavedSiteChangedViewState
 import com.duckduckgo.app.browser.webshare.WebShareChooser
 import com.duckduckgo.app.browser.webview.WebContentDebugging
 import com.duckduckgo.app.browser.webview.WebViewBlobDownloadFeature
+import com.duckduckgo.app.browser.webview.safewebview.SafeWebViewFeature
 import com.duckduckgo.app.cta.ui.*
 import com.duckduckgo.app.di.AppCoroutineScope
 import com.duckduckgo.app.fire.fireproofwebsite.data.FireproofWebsiteEntity
@@ -491,6 +491,9 @@ class BrowserTabFragment :
     @Inject
     lateinit var singlePrintSafeguardFeature: SinglePrintSafeguardFeature
 
+    @Inject
+    lateinit var safeWebViewFeature: SafeWebViewFeature
+
     /**
      * We use this to monitor whether the user was seeing the in-context Email Protection signup prompt
      * This is needed because the activity stack will be cleared if an external link is opened in our browser
@@ -1237,7 +1240,7 @@ class BrowserTabFragment :
         url: String,
         headers: Map<String, String>,
     ) {
-        clientBrandHintProvider.setOn(webView?.settings, url)
+        clientBrandHintProvider.setOn(webView?.safeSettings, url)
         hideKeyboard()
         renderer.hideFindInPage()
         viewModel.registerDaxBubbleCtaDismissed()
@@ -1362,7 +1365,7 @@ class BrowserTabFragment :
                 dismissAppLinkSnackBar()
                 val navList = webView?.safeCopyBackForwardList()
                 val currentIndex = navList?.currentIndex ?: 0
-                clientBrandHintProvider.setOn(webView?.settings, navList?.getItemAtIndex(currentIndex - 1)?.url.toString())
+                clientBrandHintProvider.setOn(webView?.safeSettings, navList?.getItemAtIndex(currentIndex - 1)?.url.toString())
                 viewModel.refreshBrowserError()
                 webView?.goBackOrForward(-it.steps)
             }
@@ -1371,7 +1374,7 @@ class BrowserTabFragment :
                 dismissAppLinkSnackBar()
                 val navList = webView?.safeCopyBackForwardList()
                 val currentIndex = navList?.currentIndex ?: 0
-                clientBrandHintProvider.setOn(webView?.settings, navList?.getItemAtIndex(currentIndex + 1)?.url.toString())
+                clientBrandHintProvider.setOn(webView?.safeSettings, navList?.getItemAtIndex(currentIndex + 1)?.url.toString())
                 viewModel.refreshBrowserError()
                 webView?.goForward()
             }
@@ -2219,6 +2222,7 @@ class BrowserTabFragment :
         ).findViewById(R.id.browserWebView) as DuckDuckGoWebView
 
         webView?.let {
+            it.isSafeWebViewEnabled = safeWebViewFeature.self().isEnabled()
             it.webViewClient = webViewClient
             it.webChromeClient = webChromeClient
             it.clearSslPreferences()
@@ -2619,7 +2623,7 @@ class BrowserTabFragment :
         view: View,
         menuInfo: ContextMenu.ContextMenuInfo?,
     ) {
-        webView?.hitTestResult?.let {
+        webView?.safeHitTestResult?.let {
             val target = getLongPressTarget(it) ?: return
             viewModel.userLongPressedInWebView(target, menu)
         }
@@ -2662,7 +2666,7 @@ class BrowserTabFragment :
 
     override fun onContextItemSelected(item: MenuItem): Boolean {
         runCatching {
-            webView?.hitTestResult?.let {
+            webView?.safeHitTestResult?.let {
                 val target = getLongPressTarget(it)
                 if (target != null && viewModel.userSelectedItemFromLongPressMenu(target, item)) {
                     return true
@@ -2885,10 +2889,10 @@ class BrowserTabFragment :
         url: String?,
         isDesktop: Boolean,
     ) {
-        val currentAgent = webView?.settings?.userAgentString
+        val currentAgent = webView?.safeSettings?.userAgentString
         val newAgent = userAgentProvider.userAgent(url, isDesktop)
         if (newAgent != currentAgent) {
-            webView?.settings?.userAgentString = newAgent
+            webView?.safeSettings?.userAgentString = newAgent
         }
         Timber.d("User Agent is $newAgent")
     }
@@ -3180,7 +3184,7 @@ class BrowserTabFragment :
         val navList = webView?.safeCopyBackForwardList()
         val currentIndex = navList?.currentIndex ?: 0
 
-        clientBrandHintProvider.setOn(webView?.settings, navList?.getItemAtIndex(currentIndex + stepsToMove)?.url.toString())
+        clientBrandHintProvider.setOn(webView?.safeSettings, navList?.getItemAtIndex(currentIndex + stepsToMove)?.url.toString())
         webView?.goBackOrForward(stepsToMove)
     }
 
@@ -4033,7 +4037,7 @@ class BrowserTabFragment :
         if (viewModel.isPrinting()) return
 
         (activity?.getSystemService(Context.PRINT_SERVICE) as? PrintManager)?.let { printManager ->
-            webView?.createPrintDocumentAdapter(url)?.let { webViewPrintDocumentAdapter ->
+            webView?.createSafePrintDocumentAdapter(url)?.let { webViewPrintDocumentAdapter ->
 
                 val printAdapter = if (singlePrintSafeguardFeature.self().isEnabled()) {
                     PrintDocumentAdapterFactory.createPrintDocumentAdapter(

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

@@ -18,17 +18,25 @@ package com.duckduckgo.app.browser
 
 import android.annotation.SuppressLint
 import android.content.Context
+import android.os.Message
+import android.print.PrintDocumentAdapter
 import android.util.AttributeSet
 import android.view.MotionEvent
 import android.view.inputmethod.EditorInfo
 import android.view.inputmethod.InputConnection
+import android.webkit.DownloadListener
+import android.webkit.WebBackForwardList
+import android.webkit.WebChromeClient
+import android.webkit.WebSettings
 import android.webkit.WebView
+import android.webkit.WebViewClient
 import androidx.core.view.NestedScrollingChild3
 import androidx.core.view.NestedScrollingChildHelper
 import androidx.core.view.ViewCompat
 import androidx.webkit.WebViewCompat
 import androidx.webkit.WebViewCompat.WebMessageListener
 import androidx.webkit.WebViewFeature
+import com.duckduckgo.app.browser.navigation.safeCopyBackForwardList
 import com.duckduckgo.browser.api.WebViewVersionProvider
 import com.duckduckgo.common.utils.DispatcherProvider
 import com.duckduckgo.common.utils.extensions.compareSemanticVersion
@@ -57,7 +65,8 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
     private var nestedScrollHelper: NestedScrollingChildHelper = NestedScrollingChildHelper(this)
     private val helper = CoordinatorLayoutHelper()
 
-    var isDestroyed: Boolean = false
+    private var isDestroyed: Boolean = false
+    var isSafeWebViewEnabled: Boolean = false
 
     constructor(context: Context) : this(context, null)
     constructor(
@@ -73,10 +82,136 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild3 {
     }
 
     override fun destroy() {
-        isDestroyed = true
+        isDestroyed = true && isSafeWebViewEnabled
         super.destroy()
     }
 
+    override fun stopLoading() {
+        if (!isDestroyed) {
+            super.stopLoading()
+        }
+    }
+
+    override fun onPause() {
+        if (!isDestroyed) {
+            super.onPause()
+        }
+    }
+
+    override fun onResume() {
+        if (!isDestroyed) {
+            super.onResume()
+        }
+    }
+
+    override fun loadUrl(url: String) {
+        if (!isDestroyed) {
+            super.loadUrl(url)
+        }
+    }
+
+    override fun loadUrl(
+        url: String,
+        additionalHttpHeaders: Map<String, String>,
+    ) {
+        if (!isDestroyed) {
+            super.loadUrl(url, additionalHttpHeaders)
+        }
+    }
+
+    override fun reload() {
+        if (!isDestroyed) {
+            super.reload()
+        }
+    }
+
+    override fun goForward() {
+        if (!isDestroyed) {
+            super.goForward()
+        }
+    }
+
+    override fun goBackOrForward(steps: Int) {
+        if (!isDestroyed) {
+            super.goBackOrForward(steps)
+        }
+    }
+
+    override fun findAllAsync(find: String) {
+        if (!isDestroyed) {
+            super.findAllAsync(find)
+        }
+    }
+
+    override fun findNext(forward: Boolean) {
+        if (!isDestroyed) {
+            super.findNext(forward)
+        }
+    }
+
+    override fun clearSslPreferences() {
+        if (!isDestroyed) {
+            super.clearSslPreferences()
+        }
+    }
+
+    override fun setDownloadListener(listener: DownloadListener?) {
+        if (!isDestroyed) {
+            super.setDownloadListener(listener)
+        }
+    }
+
+    override fun requestFocusNodeHref(hrefMsg: Message?) {
+        if (!isDestroyed) {
+            super.requestFocusNodeHref(hrefMsg)
+        }
+    }
+
+    override fun setWebChromeClient(client: WebChromeClient?) {
+        if (!isDestroyed) {
+            super.setWebChromeClient(client)
+        }
+    }
+
+    override fun setWebViewClient(client: WebViewClient) {
+        if (!isDestroyed) {
+            super.setWebViewClient(client)
+        }
+    }
+
+    override fun setFindListener(listener: FindListener?) {
+        if (!isDestroyed) {
+            super.setFindListener(listener)
+        }
+    }
+
+    override fun getUrl(): String? {
+        if (isDestroyed) return null
+        return super.getUrl()
+    }
+
+    fun safeCopyBackForwardList(): WebBackForwardList? {
+        if (isDestroyed) return null
+        return (this as WebView).safeCopyBackForwardList()
+    }
+
+    fun createSafePrintDocumentAdapter(documentName: String): PrintDocumentAdapter? {
+        if (isDestroyed) return null
+        return createPrintDocumentAdapter(documentName)
+    }
+
+    val safeSettings: WebSettings?
+        get() {
+            if (isDestroyed) return null
+            return getSettings()
+        }
+
+    val safeHitTestResult: HitTestResult?
+        get() {
+            if (isDestroyed) return null
+            return getHitTestResult()
+        }
+
     fun setBottomMatchingBehaviourEnabled(value: Boolean) {
         helper.setBottomMatchingBehaviourEnabled(value)
     }

app/src/main/java/com/duckduckgo/app/browser/webview/safewebview/SafeWebViewFeature.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024 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.webview.safewebview
+
+import com.duckduckgo.anvil.annotations.ContributesRemoteFeature
+import com.duckduckgo.di.scopes.AppScope
+import com.duckduckgo.feature.toggles.api.Toggle
+
+@ContributesRemoteFeature(
+    scope = AppScope::class,
+    featureName = "safeWebView",
+)
+
+interface SafeWebViewFeature {
+
+    @Toggle.DefaultValue(true)
+    fun self(): Toggle
+}