Android webview tries to switch to CE context

android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java

Index: android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java
diff --git a/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java b/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java
index 2ef597bfab1af55fa202d279a6c2850544ddf6dd..11795ad21c7f4f24db483815af791998bf524e90 100644
--- a/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java
+++ b/android_webview/glue/java/src/com/android/webview/chromium/WebViewChromiumFactoryProvider.java
@@ -10,6 +10,7 @@ import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
+import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
@@ -66,6 +67,7 @@ import org.chromium.net.NetworkChangeNotifier;
 import org.chromium.ui.base.ResourceBundle;
 
 import java.io.File;
+import java.lang.reflect.InvocationTargetException;
 import java.util.Queue;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentLinkedQueue;
@@ -199,12 +201,11 @@ public class WebViewChromiumFactoryProvider implements WebViewFactoryProvider {
     private void initialize(WebViewDelegate webViewDelegate) {
         mWebViewDelegate = webViewDelegate;
 
-        checkStorageIsNotDeviceProtected(mWebViewDelegate.getApplication());
+        Context ctx = switchToCredentialProtectedStorage(
+                mWebViewDelegate.getApplication().getApplicationContext());
 
         // WebView needs to make sure to always use the wrapped application context.
-        ContextUtils.initApplicationContext(
-                ResourcesContextWrapperFactory.get(
-                        mWebViewDelegate.getApplication().getApplicationContext()));
+        ContextUtils.initApplicationContext(ResourcesContextWrapperFactory.get(ctx));
 
         if (isBuildDebuggable()) {
             // Suppress the StrictMode violation as this codepath is only hit on debuggable builds.
@@ -253,12 +254,38 @@ public class WebViewChromiumFactoryProvider implements WebViewFactoryProvider {
         // Now safe to use WebView data directory.
     }
 
-    static void checkStorageIsNotDeviceProtected(Context context) {
+    // Webview must use a CredentialEncrypted Context. If context is a CE context, then simply
+    // return it without modification. Otherwise, create a new CE context and return that instead.
+    static Context switchToCredentialProtectedStorage(Context context) {
+        // For versions N+, android webview must use a CredentialEncrypted Context
         if ((Build.VERSION.CODENAME.equals("N") || Build.VERSION.SDK_INT > Build.VERSION_CODES.M)
                 && context.isDeviceProtectedStorage()) {
-            throw new IllegalArgumentException(
-                    "WebView cannot be used with device protected storage");
+            ApplicationInfo appInfo = context.getApplicationInfo();
+            try {
+                // Check the manifest flag android:defaultToDeviceProtectedStorage

[Torne, 2016/09/21 12:04:18]

I'm not sure there's any point in actually checking this. The only time the
application context is going to be device-protected storage is when it's
defaulting to it.

[Nate Fischer, 2016/09/22 04:21:12]

Ok, I misunderstood the bug report. I've removed the check.

+                boolean defaultsToDeviceProtection =
+                        (Boolean) appInfo.getClass()
+                                .getMethod("isDefaultToDeviceProtectedStorage")
+                                .invoke(appInfo);
+                // For system applications using the flag, attempt to use a CE context if it's
+                // available
+                if (defaultsToDeviceProtection) {
+                    context = context.createCredentialProtectedStorageContext();
+                }
+
+                // If this application does not default to DE storage, or we were unable to create a
+                // CE context
+                if (context.isDeviceProtectedStorage()) {
+                    throw new IllegalArgumentException(
+                            "WebView cannot be used with device protected storage");
+                }
+            } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException
+                    | IllegalArgumentException e) {
+                throw new IllegalArgumentException(
+                        "WebView cannot be used with device protected storage");
+            }
         }
+        return context;
     }
 
     private static boolean isBuildDebuggable() {