[aw] Ensure that WebView APIs do not crash if called after destruction.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index a4d1119e32cdfbe30ec222a74c9a11ade37e1302..b67a0c30f1e490a7102d654291a565f5cf83b2d6 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -251,6 +251,10 @@ public class AwContents {
     // when in this state.
     private boolean mTemporarilyDetached;
 
+    // True when this AwContents has been destroyed.
+    // Do not use directly, call isDestroyed() instead.
+    private boolean mIsDestroyed = false;
+
     private static final class DestroyRunnable implements Runnable {
         private final long mNativeAwContents;
         private DestroyRunnable(long nativeAwContents) {
@@ -453,8 +457,7 @@ public class AwContents {
 
         @Override
         public void scrollNativeTo(int x, int y) {
-            if (mNativeAwContents == 0) return;
-            nativeScrollTo(mNativeAwContents, x, y);
+            if (!isDestroyed()) nativeScrollTo(mNativeAwContents, x, y);
         }
 
         @Override
@@ -511,7 +514,7 @@ public class AwContents {
     private class AwComponentCallbacks implements ComponentCallbacks2 {
         @Override
         public void onTrimMemory(final int level) {
-            if (mNativeAwContents == 0) return;
+            if (isDestroyed()) return;
             boolean visibleRectEmpty = getGlobalVisibleRect().isEmpty();
             final boolean visible = mIsViewVisible && mIsWindowVisible && !visibleRectEmpty;
             nativeTrimMemory(mNativeAwContents, level, visible);
@@ -591,6 +594,7 @@ public class AwContents {
                     @Override
                     public void onGestureZoomSupportChanged(
                             boolean supportsDoubleTapZoom, boolean supportsMultiTouchZoom) {
+                        if (isDestroyed()) return;
                         mContentViewCore.updateDoubleTapSupport(supportsDoubleTapZoom);
                         mContentViewCore.updateMultiTouchZoomSupport(supportsMultiTouchZoom);
                     }
@@ -636,10 +640,12 @@ public class AwContents {
 
     /**
      * Transitions this {@link AwContents} to fullscreen mode and returns the
-     * {@link View} where the contents will be drawn while in fullscreen.
+     * {@link View} where the contents will be drawn while in fullscreen, or null
+     * if this AwContents has already been destroyed.
      */
     View enterFullScreen() {
         assert !isFullScreen();
+        if (isDestroyed()) return null;
 
         // Detach to tear down the GL functor if this is still associated with the old
         // container view. It will be recreated during the next call to onDraw attached to
@@ -666,7 +672,7 @@ public class AwContents {
      * in the WebView.
      */
     void exitFullScreen() {
-        if (!isFullScreen())
+        if (!isFullScreen() || isDestroyed())
             // exitFullScreen() can be called without a prior call to enterFullScreen() if a
             // "misbehave" app overrides onShowCustomView but does not add the custom view to
             // the window. Exiting avoids a crash.
@@ -747,7 +753,7 @@ public class AwContents {
      */
     private void setNewAwContents(long newAwContentsPtr) {
         if (mNativeAwContents != 0) {
-            destroy();
+            destroyNatives();
             mContentViewCore = null;
             mWebContents = null;
             mNavigationController = null;
@@ -864,9 +870,17 @@ public class AwContents {
     }
 
     /**
-     * Deletes the native counterpart of this object.
+     * Destroys this object and deletes its native counterpart.
      */
     public void destroy() {
+        mIsDestroyed = true;
+        destroyNatives();
+    }
+
+    /**
+     * Deletes the native counterpart of this object.
+     */
+    private void destroyNatives() {
         if (mCleanupReference != null) {
             assert mNativeAwContents != 0;
             // If we are attached, we have to call native detach to clean up
@@ -875,21 +889,37 @@ public class AwContents {
                 nativeOnDetachedFromWindow(mNativeAwContents);
             }
 
-            // We explicitly do not null out the mContentViewCore reference here
-            // because ContentViewCore already has code to deal with the case
-            // methods are called on it after it's been destroyed, and other
-            // code relies on AwContents.mContentViewCore to be non-null.
             mContentViewCore.destroy();
+            mContentViewCore = null;
             mNativeAwContents = 0;
+            mWebContents = null;
+            mNavigationController = null;
 
             mCleanupReference.cleanupNow();
             mCleanupReference = null;
         }
 
-        assert !mContentViewCore.isAlive();
+        assert mContentViewCore == null;
+        assert mWebContents == null;
+        assert mNavigationController == null;
         assert mNativeAwContents == 0;
     }
 
+    private boolean isDestroyed() {
+        if (mIsDestroyed) {
+            assert mContentViewCore == null;
+            assert mWebContents == null;
+            assert mNavigationController == null;
+            assert mNativeAwContents == 0;
+        } else {
+            assert mContentViewCore != null;
+            assert mWebContents != null;
+            assert mNavigationController != null;
+            assert mNativeAwContents != 0;
+        }
+        return mIsDestroyed;
+    }
+
     @VisibleForTesting
     public ContentViewCore getContentViewCore() {
         return mContentViewCore;
@@ -911,10 +941,7 @@ public class AwContents {
     }
 
     public AwPdfExporter getPdfExporter() {
-        // mNativeAwContents can be null, due to destroy().
-        if (mNativeAwContents == 0) {
-            return null;
-        }
+        if (isDestroyed()) return null;
         if (mAwPdfExporter == null) {
             mAwPdfExporter = new AwPdfExporter(mContainerView);
             nativeCreatePdfExporter(mNativeAwContents, mAwPdfExporter);
@@ -945,7 +972,7 @@ public class AwContents {
      * to ensure backwards compatible behavior.
      */
     public void disableJavascriptInterfacesInspection() {
-        mContentViewCore.setAllowJavascriptInterfacesInspection(false);
+        if (!isDestroyed()) mContentViewCore.setAllowJavascriptInterfacesInspection(false);
     }
 
     /**
@@ -960,7 +987,7 @@ public class AwContents {
     public long getAwDrawGLViewContext() {
         // Only called during early construction, so client should not have had a chance to
         // call destroy yet.
-        assert mNativeAwContents != 0;
+        assert !isDestroyed();
 
         // Using the native pointer as the returned viewContext. This is matched by the
         // reinterpret_cast back to BrowserViewRenderer pointer in the native DrawGLFunction.
@@ -999,15 +1026,14 @@ public class AwContents {
     }
 
     public Picture capturePicture() {
-        if (mNativeAwContents == 0) return null;
+        if (isDestroyed()) return null;
         return new AwPicture(nativeCapturePicture(mNativeAwContents,
                 mScrollOffsetManager.computeHorizontalScrollRange(),
                 mScrollOffsetManager.computeVerticalScrollRange()));
     }
 
     public void clearView() {
-        if (mNativeAwContents == 0) return;
-        nativeClearView(mNativeAwContents);
+        if (!isDestroyed()) nativeClearView(mNativeAwContents);
     }
 
     /**
@@ -1016,7 +1042,7 @@ public class AwContents {
      * @param invalidationOnly Flag to call back only on invalidation without providing a picture.
      */
     public void enableOnNewPicture(boolean enabled, boolean invalidationOnly) {
-        if (mNativeAwContents == 0) return;
+        if (isDestroyed()) return;
         if (invalidationOnly) {
             mPictureListenerContentProvider = null;
         } else if (enabled && mPictureListenerContentProvider == null) {
@@ -1031,18 +1057,15 @@ public class AwContents {
     }
 
     public void findAllAsync(String searchString) {
-        if (mNativeAwContents == 0) return;
-        nativeFindAllAsync(mNativeAwContents, searchString);
+        if (!isDestroyed()) nativeFindAllAsync(mNativeAwContents, searchString);
     }
 
     public void findNext(boolean forward) {
-        if (mNativeAwContents == 0) return;
-        nativeFindNext(mNativeAwContents, forward);
+        if (!isDestroyed()) nativeFindNext(mNativeAwContents, forward);
     }
 
     public void clearMatches() {
-        if (mNativeAwContents == 0) return;
-        nativeClearMatches(mNativeAwContents);
+        if (!isDestroyed()) nativeClearMatches(mNativeAwContents);
     }
 
     /**
@@ -1064,8 +1087,7 @@ public class AwContents {
                 ThreadUtils.runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
-                        if (mNativeAwContents == 0) return;
-                        nativeAddVisitedLinks(mNativeAwContents, value);
+                        if (!isDestroyed()) nativeAddVisitedLinks(mNativeAwContents, value);
                     }
                 });
             }
@@ -1081,6 +1103,8 @@ public class AwContents {
      * @param params Parameters for this load.
      */
     public void loadUrl(LoadUrlParams params) {
+        if (isDestroyed()) return;
+
         if (params.getLoadUrlType() == LoadUrlParams.LOAD_TYPE_DATA &&
                 !params.isBaseUrlDataScheme()) {
             // This allows data URLs with a non-data base URL access to file:///android_asset/ and
@@ -1119,10 +1143,8 @@ public class AwContents {
             }
         }
 
-        if (mNativeAwContents != 0) {
-            nativeSetExtraHeadersForUrl(
-                    mNativeAwContents, params.getUrl(), params.getExtraHttpRequestHeadersString());
-        }
+        nativeSetExtraHeadersForUrl(
+                mNativeAwContents, params.getUrl(), params.getExtraHttpRequestHeadersString());
         params.setExtraHeaders(new HashMap<String, String>());
 
         mNavigationController.loadUrl(params);
@@ -1149,6 +1171,7 @@ public class AwContents {
      * @return The URL of the current page or null if it's empty.
      */
     public String getUrl() {
+        if (isDestroyed()) return null;
         String url =  mWebContents.getUrl();
         if (url == null || url.trim().isEmpty()) return null;
         return url;
@@ -1160,7 +1183,7 @@ public class AwContents {
 
     public void setBackgroundColor(int color) {
         mBaseBackgroundColor = color;
-        if (mNativeAwContents != 0) nativeSetBackgroundColor(mNativeAwContents, color);
+        if (!isDestroyed()) nativeSetBackgroundColor(mNativeAwContents, color);
     }
 
     /**
@@ -1174,7 +1197,7 @@ public class AwContents {
         // Do not ask the ContentViewCore for the background color, as it will always
         // report white prior to initial navigation or post destruction,  whereas we want
         // to use the client supplied base value in those cases.
-        if (mNativeAwContents == 0 || !mContentsClient.isCachedRendererBackgroundColorValid()) {
+        if (isDestroyed() || !mContentsClient.isCachedRendererBackgroundColorValid()) {
             return mBaseBackgroundColor;
         }
         return mContentsClient.getCachedRendererBackgroundColor();
@@ -1192,7 +1215,7 @@ public class AwContents {
      * @see ContentViewCore#getContentSettings()
      */
     public ContentSettings getContentSettings() {
-        return mContentViewCore.getContentSettings();
+        return isDestroyed() ? null : mContentViewCore.getContentSettings();
     }
 
     /**
@@ -1340,77 +1363,77 @@ public class AwContents {
      * @see android.webkit.WebView#stopLoading()
      */
     public void stopLoading() {
-        mWebContents.stop();
+        if (!isDestroyed()) mWebContents.stop();
     }
 
     /**
      * @see android.webkit.WebView#reload()
      */
     public void reload() {
-        mNavigationController.reload(true);
+        if (!isDestroyed()) mNavigationController.reload(true);
     }
 
     /**
      * @see android.webkit.WebView#canGoBack()
      */
     public boolean canGoBack() {
-        return mNavigationController.canGoBack();
+        return isDestroyed() ? false : mNavigationController.canGoBack();
     }
 
     /**
      * @see android.webkit.WebView#goBack()
      */
     public void goBack() {
-        mNavigationController.goBack();
+        if (!isDestroyed()) mNavigationController.goBack();
     }
 
     /**
      * @see android.webkit.WebView#canGoForward()
      */
     public boolean canGoForward() {
-        return mNavigationController.canGoForward();
+        return isDestroyed() ? false : mNavigationController.canGoForward();
     }
 
     /**
      * @see android.webkit.WebView#goForward()
      */
     public void goForward() {
-        mNavigationController.goForward();
+        if (!isDestroyed()) mNavigationController.goForward();
     }
 
     /**
      * @see android.webkit.WebView#canGoBackOrForward(int)
      */
     public boolean canGoBackOrForward(int steps) {
-        return mNavigationController.canGoToOffset(steps);
+        return isDestroyed() ? false : mNavigationController.canGoToOffset(steps);
     }
 
     /**
      * @see android.webkit.WebView#goBackOrForward(int)
      */
     public void goBackOrForward(int steps) {
-        mNavigationController.goToOffset(steps);
+        if (!isDestroyed()) mNavigationController.goToOffset(steps);
     }
 
     /**
      * @see android.webkit.WebView#pauseTimers()
      */
     public void pauseTimers() {
-        ContentViewStatics.setWebKitSharedTimersSuspended(true);
+        if (!isDestroyed()) ContentViewStatics.setWebKitSharedTimersSuspended(true);
     }
 
     /**
      * @see android.webkit.WebView#resumeTimers()
      */
     public void resumeTimers() {
-        ContentViewStatics.setWebKitSharedTimersSuspended(false);
+        if (!isDestroyed()) ContentViewStatics.setWebKitSharedTimersSuspended(false);
     }
 
     /**
      * @see android.webkit.WebView#onPause()
      */
     public void onPause() {
-        if (mIsPaused || mNativeAwContents == 0) return;
+        if (mIsPaused || isDestroyed()) return;
         mIsPaused = true;
         nativeSetIsPaused(mNativeAwContents, mIsPaused);
     }
@@ -1419,7 +1442,7 @@ public class AwContents {
      * @see android.webkit.WebView#onResume()
      */
     public void onResume() {
-        if (!mIsPaused || mNativeAwContents == 0) return;
+        if (!mIsPaused || isDestroyed()) return;
         mIsPaused = false;
         nativeSetIsPaused(mNativeAwContents, mIsPaused);
     }
@@ -1459,13 +1482,11 @@ public class AwContents {
      * @param includeDiskFiles if false, only the RAM cache is cleared
      */
     public void clearCache(boolean includeDiskFiles) {
-        if (mNativeAwContents == 0) return;
-        nativeClearCache(mNativeAwContents, includeDiskFiles);
+        if (!isDestroyed()) nativeClearCache(mNativeAwContents, includeDiskFiles);
     }
 
     public void documentHasImages(Message message) {
-        if (mNativeAwContents == 0) return;
-        nativeDocumentHasImages(mNativeAwContents, message);
+        if (!isDestroyed()) nativeDocumentHasImages(mNativeAwContents, message);
     }
 
     public void saveWebArchive(
@@ -1490,6 +1511,7 @@ public class AwContents {
     }
 
     public String getOriginalUrl() {
+        if (isDestroyed()) return null;
         NavigationHistory history = mNavigationController.getNavigationHistory();
         int currentIndex = history.getCurrentEntryIndex();
         if (currentIndex >= 0 && currentIndex < history.getEntryCount()) {
@@ -1502,21 +1524,21 @@ public class AwContents {
      * @see ContentViewCore#getNavigationHistory()
      */
     public NavigationHistory getNavigationHistory() {
-        return mNavigationController.getNavigationHistory();
+        return isDestroyed() ? null : mNavigationController.getNavigationHistory();
     }
 
     /**
      * @see android.webkit.WebView#getTitle()
      */
     public String getTitle() {
-        return mWebContents.getTitle();
+        return isDestroyed() ? null : mWebContents.getTitle();
     }
 
     /**
      * @see android.webkit.WebView#clearHistory()
      */
     public void clearHistory() {
-        mNavigationController.clearHistory();
+        if (!isDestroyed()) mNavigationController.clearHistory();
     }
 
     public String[] getHttpAuthUsernamePassword(String host, String realm) {
@@ -1534,15 +1556,15 @@ public class AwContents {
      * @see android.webkit.WebView#getCertificate()
      */
     public SslCertificate getCertificate() {
-        if (mNativeAwContents == 0) return null;
-        return SslUtil.getCertificateFromDerBytes(nativeGetCertificate(mNativeAwContents));
+        return isDestroyed() ? null
+                : SslUtil.getCertificateFromDerBytes(nativeGetCertificate(mNativeAwContents));
     }
 
     /**
      * @see android.webkit.WebView#clearSslPreferences()
      */
     public void clearSslPreferences() {
-        mNavigationController.clearSslPreferences();
+        if (!isDestroyed()) mNavigationController.clearSslPreferences();
     }
 
     // TODO(sgurun) remove after this rolls in. To keep internal tree happy.
@@ -1555,7 +1577,7 @@ public class AwContents {
      * garbage allocation on repeated calls.
      */
     public HitTestData getLastHitTestResult() {
-        if (mNativeAwContents == 0) return null;
+        if (isDestroyed()) return null;
         nativeUpdateLastHitTestData(mNativeAwContents);
         return mPossiblyStaleHitTestData;
     }
@@ -1564,7 +1586,7 @@ public class AwContents {
      * @see android.webkit.WebView#requestFocusNodeHref()
      */
     public void requestFocusNodeHref(Message msg) {
-        if (msg == null || mNativeAwContents == 0) return;
+        if (msg == null || isDestroyed()) return;
 
         nativeUpdateLastHitTestData(mNativeAwContents);
         Bundle data = msg.getData();
@@ -1583,7 +1605,7 @@ public class AwContents {
      * @see android.webkit.WebView#requestImageRef()
      */
     public void requestImageRef(Message msg) {
-        if (msg == null || mNativeAwContents == 0) return;
+        if (msg == null || isDestroyed()) return;
 
         nativeUpdateLastHitTestData(mNativeAwContents);
         Bundle data = msg.getData();
@@ -1678,6 +1700,7 @@ public class AwContents {
     // This method uses the term 'zoom' for legacy reasons, but relates
     // to what chrome calls the 'page scale factor'.
     public boolean zoomBy(float delta) {
+        if (isDestroyed()) return false;
         if (delta < 0.01f || delta > 100.0f) {
             throw new IllegalStateException("zoom delta value outside [0.01, 100] range.");
         }
@@ -1688,14 +1711,14 @@ public class AwContents {
      * @see android.webkit.WebView#invokeZoomPicker()
      */
     public void invokeZoomPicker() {
-        mContentViewCore.invokeZoomPicker();
+        if (!isDestroyed()) mContentViewCore.invokeZoomPicker();
     }
 
     /**
      * @see android.webkit.WebView#preauthorizePermission(Uri, long)
      */
     public void preauthorizePermission(Uri origin, long resources) {
-        if (mNativeAwContents == 0) return;
+        if (isDestroyed()) return;
         nativePreauthorizePermission(mNativeAwContents, origin.toString(), resources);
     }
 
@@ -1703,6 +1726,7 @@ public class AwContents {
      * @see ContentViewCore.evaluateJavaScript(String, JavaScriptCallback)
      */
     public void evaluateJavaScript(String script, final ValueCallback<String> callback) {
+        if (isDestroyed()) return;
         JavaScriptCallback jsCallback = null;
         if (callback != null) {
             jsCallback = new JavaScriptCallback() {
@@ -1718,7 +1742,7 @@ public class AwContents {
 
     // TODO(boliu): Remove this once Android side no longer calls this.
     public void evaluateJavaScriptEvenIfNotYetNavigated(String script) {
-        mWebContents.evaluateJavaScript(script, null);
+        if (!isDestroyed()) mWebContents.evaluateJavaScript(script, null);
     }
 
     //--------------------------------------------------------------------------------------------
@@ -1743,7 +1767,7 @@ public class AwContents {
      * @see android.view.View#onGenericMotionEvent()
      */
     public boolean onGenericMotionEvent(MotionEvent event) {
-        return mContentViewCore.onGenericMotionEvent(event);
+        return isDestroyed() ? false : mContentViewCore.onGenericMotionEvent(event);
     }
 
     /**
@@ -1822,14 +1846,12 @@ public class AwContents {
 
     private void setViewVisibilityInternal(boolean visible) {
         mIsViewVisible = visible;
-        if (mNativeAwContents == 0) return;
-        nativeSetViewVisibility(mNativeAwContents, mIsViewVisible);
+        if (!isDestroyed()) nativeSetViewVisibility(mNativeAwContents, mIsViewVisible);
     }
 
     private void setWindowVisibilityInternal(boolean visible) {
         mIsWindowVisible = visible;
-        if (mNativeAwContents == 0) return;
-        nativeSetWindowVisibility(mNativeAwContents, mIsWindowVisible);
+        if (!isDestroyed()) nativeSetWindowVisibility(mNativeAwContents, mIsWindowVisible);
     }
 
     /**
@@ -1842,7 +1864,7 @@ public class AwContents {
      * @return False if saving state failed.
      */
     public boolean saveState(Bundle outState) {
-        if (mNativeAwContents == 0 || outState == null) return false;
+        if (isDestroyed() || outState == null) return false;
 
         byte[] state = nativeGetOpaqueState(mNativeAwContents);
         if (state == null) return false;
@@ -1857,7 +1879,7 @@ public class AwContents {
      * @return False if restoring state failed.
      */
     public boolean restoreState(Bundle inState) {
-        if (mNativeAwContents == 0 || inState == null) return false;
+        if (isDestroyed() || inState == null) return false;
 
         byte[] state = inState.getByteArray(SAVE_RESTORE_STATE_KEY);
         if (state == null) return false;
@@ -1878,6 +1900,7 @@ public class AwContents {
      */
     public void addPossiblyUnsafeJavascriptInterface(Object object, String name,
             Class<? extends Annotation> requiredAnnotation) {
+        if (isDestroyed()) return;
         mContentViewCore.addPossiblyUnsafeJavascriptInterface(object, name, requiredAnnotation);
     }
 
@@ -1885,7 +1908,7 @@ public class AwContents {
      * @see android.webkit.WebView#removeJavascriptInterface(String)
      */
     public void removeJavascriptInterface(String interfaceName) {
-        mContentViewCore.removeJavascriptInterface(interfaceName);
+        if (!isDestroyed()) mContentViewCore.removeJavascriptInterface(interfaceName);
     }
 
     /**
@@ -1895,32 +1918,33 @@ public class AwContents {
      * @return The AccessibilityNodeProvider, if available, or null otherwise.
      */
     public AccessibilityNodeProvider getAccessibilityNodeProvider() {
-        return mContentViewCore.getAccessibilityNodeProvider();
+        return isDestroyed() ? null : mContentViewCore.getAccessibilityNodeProvider();
     }
 
     /**
      * @see android.webkit.WebView#onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo)
      */
     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
-        mContentViewCore.onInitializeAccessibilityNodeInfo(info);
+        if (!isDestroyed()) mContentViewCore.onInitializeAccessibilityNodeInfo(info);
     }
 
     /**
      * @see android.webkit.WebView#onInitializeAccessibilityEvent(AccessibilityEvent)
      */
     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
-        mContentViewCore.onInitializeAccessibilityEvent(event);
+        if (!isDestroyed()) mContentViewCore.onInitializeAccessibilityEvent(event);
     }
 
     public boolean supportsAccessibilityAction(int action) {
-        return mContentViewCore.supportsAccessibilityAction(action);
+        return isDestroyed() ? false : mContentViewCore.supportsAccessibilityAction(action);
     }
 
     /**
      * @see android.webkit.WebView#performAccessibilityAction(int, Bundle)
      */
     public boolean performAccessibilityAction(int action, Bundle arguments) {
-        return mContentViewCore.performAccessibilityAction(action, arguments);
+        return isDestroyed() ? false
+                : mContentViewCore.performAccessibilityAction(action, arguments);
     }
 
     /**
@@ -1933,8 +1957,7 @@ public class AwContents {
     }
 
     public void setNetworkAvailable(boolean networkUp) {
-        if (mNativeAwContents == 0) return;
-        nativeSetJsOnlineProperty(mNativeAwContents, networkUp);
+        if (!isDestroyed()) nativeSetJsOnlineProperty(mNativeAwContents, networkUp);
     }
 
     //--------------------------------------------------------------------------------------------
@@ -1985,7 +2008,7 @@ public class AwContents {
                             mBrowserContext.getGeolocationPermissions().deny(origin);
                         }
                     }
-                    if (mNativeAwContents == 0) return;
+                    if (isDestroyed()) return;
                     nativeInvokeGeolocationCallback(mNativeAwContents, allow, origin);
                 }
             });
@@ -1994,7 +2017,7 @@ public class AwContents {
 
     @CalledByNative
     private void onGeolocationPermissionsShowPrompt(String origin) {
-        if (mNativeAwContents == 0) return;
+        if (isDestroyed()) return;
         AwGeolocationPermissions permissions = mBrowserContext.getGeolocationPermissions();
         // Reject if geoloaction is disabled, or the origin has a retained deny
         if (!mSettings.getGeolocationEnabled()) {
@@ -2157,7 +2180,7 @@ public class AwContents {
     }
 
     private void saveWebArchiveInternal(String path, final ValueCallback<String> callback) {
-        if (path == null || mNativeAwContents == 0) {
+        if (path == null || isDestroyed()) {
             ThreadUtils.runOnUiThread(new Runnable() {
                 @Override
                 public void run() {
@@ -2204,11 +2227,11 @@ public class AwContents {
     }
 
     public void extractSmartClipData(int x, int y, int width, int height) {
-        mContentViewCore.extractSmartClipData(x, y, width, height);
+        if (!isDestroyed()) mContentViewCore.extractSmartClipData(x, y, width, height);
     }
 
     public void setSmartClipDataListener(ContentViewCore.SmartClipDataListener listener) {
-        mContentViewCore.setSmartClipDataListener(listener);
+        if (!isDestroyed()) mContentViewCore.setSmartClipDataListener(listener);
     }
 
     // --------------------------------------------------------------------------------------------
@@ -2224,7 +2247,7 @@ public class AwContents {
 
         @Override
         public void onDraw(Canvas canvas) {
-            if (mNativeAwContents == 0) {
+            if (isDestroyed()) {
                 canvas.drawColor(getEffectiveBackgroundColor());
                 return;
             }
@@ -2261,7 +2284,7 @@ public class AwContents {
 
         @Override
         public void requestFocus() {
-            if (mNativeAwContents == 0) return;
+            if (isDestroyed()) return;
             if (!mContainerView.isInTouchMode() && mSettings.shouldFocusFirstNode()) {
                 nativeFocusFirstNode(mNativeAwContents);
             }
@@ -2282,16 +2305,17 @@ public class AwContents {
 
         @Override
         public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
-            return mContentViewCore.onCreateInputConnection(outAttrs);
+            return isDestroyed() ? null : mContentViewCore.onCreateInputConnection(outAttrs);
         }
 
         @Override
         public boolean onKeyUp(int keyCode, KeyEvent event) {
-            return mContentViewCore.onKeyUp(keyCode, event);
+            return isDestroyed() ? false : mContentViewCore.onKeyUp(keyCode, event);
         }
 
         @Override
         public boolean dispatchKeyEvent(KeyEvent event) {
+            if (isDestroyed()) return false;
             if (isDpadEvent(event)) {
                 mSettings.setSpatialNavigationEnabled(true);
             }
@@ -2314,8 +2338,7 @@ public class AwContents {
 
         @Override
         public boolean onTouchEvent(MotionEvent event) {
-            if (mNativeAwContents == 0) return false;
-
+            if (isDestroyed()) return false;
             if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
                 mSettings.setSpatialNavigationEnabled(false);
             }
@@ -2349,22 +2372,22 @@ public class AwContents {
 
         @Override
         public boolean onHoverEvent(MotionEvent event) {
-            return mContentViewCore.onHoverEvent(event);
+            return isDestroyed() ? false : mContentViewCore.onHoverEvent(event);
         }
 
         @Override
         public boolean onGenericMotionEvent(MotionEvent event) {
-            return mContentViewCore.onGenericMotionEvent(event);
+            return isDestroyed() ? false : mContentViewCore.onGenericMotionEvent(event);
         }
 
         @Override
         public void onConfigurationChanged(Configuration newConfig) {
-            mContentViewCore.onConfigurationChanged(newConfig);
+            if (!isDestroyed()) mContentViewCore.onConfigurationChanged(newConfig);
         }
 
         @Override
         public void onAttachedToWindow() {
-            if (mNativeAwContents == 0) return;
+            if (isDestroyed()) return;
             if (mIsAttachedToWindow) {
                 Log.w(TAG, "onAttachedToWindow called when already attached. Ignoring");
                 return;
@@ -2383,15 +2406,14 @@ public class AwContents {
 
         @Override
         public void onDetachedFromWindow() {
+            if (isDestroyed()) return;
             if (!mIsAttachedToWindow) {
                 Log.w(TAG, "onDetachedFromWindow called when already detached. Ignoring");
                 return;
             }
             mIsAttachedToWindow = false;
             hideAutofillPopup();
-            if (mNativeAwContents != 0) {
-                nativeOnDetachedFromWindow(mNativeAwContents);
-            }
+            nativeOnDetachedFromWindow(mNativeAwContents);
 
             mContentViewCore.onDetachedFromWindow();
             updateHardwareAcceleratedFeaturesToggle();
@@ -2407,19 +2429,21 @@ public class AwContents {
 
         @Override
         public void onWindowFocusChanged(boolean hasWindowFocus) {
+            if (isDestroyed()) return;
             mWindowFocused = hasWindowFocus;
             mContentViewCore.onWindowFocusChanged(hasWindowFocus);
         }
 
         @Override
         public void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
+            if (isDestroyed()) return;
             mContainerViewFocused = focused;
             mContentViewCore.onFocusChanged(focused);
         }
 
         @Override
         public void onSizeChanged(int w, int h, int ow, int oh) {
-            if (mNativeAwContents == 0) return;
+            if (isDestroyed()) return;
             mScrollOffsetManager.setContainerViewSize(w, h);
             // The AwLayoutSizer needs to go first so that if we're in
             // fixedLayoutSize mode the update