[Android]: Pass serialised passwords from native as a byte array

Chrome passwords settings on Android allow the user to export
passwords. The Java settings code asks the C++ code to serialise and
send over the passwords. The serialised result is in UTF-8 within C++
but gets converted into UTF-16 for Java and then back to UTF-8 on
writing to a cache file.

This CL changes the data type from String to byte array on Java side.
This eliminates the converstion to UTF-16 and back.

Note 1: This was pointed out in
https://chromium-review.googlesource.com/c/chromium/src/+/926527/2/chrome/browser/android/password_ui_view_android.cc#222.

Note 2: This might get further simplified if https://crbug.com/817293
gets implemented, but that's not happening in M66.

Bug: 788701
Change-Id: I0799b2c5f6d7e43e9b7449322d300fb9e9d82c54
Reviewed-on: https://chromium-review.googlesource.com/940226Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539832}

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/PasswordManagerHandler.java

@@ -69,5 +69,5 @@ public interface PasswordManagerHandler {
      *
      * @param callback is called on completion, with the serialized passwords as argument.
      */
-    void serializePasswords(Callback<String> callback);
+    void serializePasswords(Callback<byte[]> callback);
 }

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/PasswordUIView.java

@@ -72,7 +72,7 @@ public final class PasswordUIView implements PasswordManagerHandler {
     }
 
     @Override
-    public void serializePasswords(Callback<String> callback) {
+    public void serializePasswords(Callback<byte[]> callback) {
         nativeHandleSerializePasswords(mNativePasswordUIViewAndroid, callback);
     }
 
@@ -116,5 +116,5 @@ public final class PasswordUIView implements PasswordManagerHandler {
     private native void nativeDestroy(long nativePasswordUIViewAndroid);
 
     private native void nativeHandleSerializePasswords(
-            long nativePasswordUIViewAndroid, Callback<String> callback);
+            long nativePasswordUIViewAndroid, Callback<byte[]> callback);
 }

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferences.java

@@ -51,14 +51,12 @@ import org.chromium.chrome.browser.preferences.TextMessagePreference;
 import org.chromium.ui.text.SpanApplier;
 import org.chromium.ui.widget.Toast;
 
-import java.io.BufferedWriter;
+import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.OutputStreamWriter;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
-import java.nio.charset.Charset;
 import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
@@ -334,10 +332,10 @@ public class SavePasswordsPreferences
      * for firing the share intent or displays an error.
      * @param serializedPasswords A string with a CSV representation of the user's passwords.
      */
-    private void shareSerializedPasswords(String serializedPasswords) {
-        AsyncTask<String, Void, ExportResult> task = new AsyncTask<String, Void, ExportResult>() {
+    private void shareSerializedPasswords(byte[] serializedPasswords) {
+        AsyncTask<byte[], Void, ExportResult> task = new AsyncTask<byte[], Void, ExportResult>() {
             @Override
-            protected ExportResult doInBackground(String... serializedPasswords) {
+            protected ExportResult doInBackground(byte[]... serializedPasswords) {
                 assert serializedPasswords.length == 1;
                 // Record the time it took to read and serialise the passwords. This excludes the
                 // time to write them into a file, to be consistent with desktop (where writing is
@@ -382,9 +380,9 @@ public class SavePasswordsPreferences
         // they arrive.
         mExportPreparationStart = System.currentTimeMillis();
         PasswordManagerHandlerProvider.getInstance().getPasswordManagerHandler().serializePasswords(
-                new Callback<String>() {
+                new Callback<byte[]>() {
                     @Override
-                    public void onResult(String serializedPasswords) {
+                    public void onResult(byte[] serializedPasswords) {
                         shareSerializedPasswords(serializedPasswords);
                     }
                 });
@@ -571,9 +569,9 @@ public class SavePasswordsPreferences
      * This method saves the contents of |serializedPasswords| into a temporary file and returns a
      * sharing URI for it. In case of failure, returns EMPTY. It should only be run on the
      * background thread of an AsyncTask, because it does I/O operations.
-     * @param serializedPasswords A string with serialized passwords in CSV format
+     * @param serializedPasswords A byte array with serialized passwords in CSV format
      */
-    private ExportResult exportPasswordsIntoFile(String serializedPasswords) {
+    private ExportResult exportPasswordsIntoFile(byte[] serializedPasswords) {
         // First ensure that the PASSWORDS_CACHE_DIR cache directory exists.
         File passwordsDir =
                 new File(ContextUtils.getApplicationContext().getCacheDir() + PASSWORDS_CACHE_DIR);
@@ -587,9 +585,9 @@ public class SavePasswordsPreferences
             return new ExportResult(e.getMessage());
         }
         tempFile.deleteOnExit();
-        try (BufferedWriter tempWriter = new BufferedWriter(new OutputStreamWriter(
-                     new FileOutputStream(tempFile), Charset.forName("UTF-8")))) {
-            tempWriter.write(serializedPasswords);
+        try (BufferedOutputStream outputStream =
+                        new BufferedOutputStream(new FileOutputStream(tempFile))) {
+            outputStream.write(serializedPasswords);
         } catch (IOException e) {
             return new ExportResult(e.getMessage());
         }

chrome/android/javatests/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferencesTest.java

@@ -107,7 +107,7 @@ public class SavePasswordsPreferencesTest {
 
         // This is set once {@link #serializePasswords()} is called.
         @Nullable
-        private Callback<String> mExportCallback;
+        private Callback<byte[]> mExportCallback;
 
         public void setSavedPasswords(ArrayList<SavedPasswordEntry> savedPasswords) {
             mSavedPasswords = savedPasswords;
@@ -117,7 +117,7 @@ public class SavePasswordsPreferencesTest {
             mSavedPasswordExeptions = savedPasswordExceptions;
         }
 
-        public Callback<String> getExportCallback() {
+        public Callback<byte[]> getExportCallback() {
             return mExportCallback;
         }
 
@@ -162,7 +162,7 @@ public class SavePasswordsPreferencesTest {
         }
 
         @Override
-        public void serializePasswords(Callback<String> callback) {
+        public void serializePasswords(Callback<byte[]> callback) {
             mExportCallback = callback;
         }
     }
@@ -738,7 +738,7 @@ public class SavePasswordsPreferencesTest {
         reauthenticateAndRequestExport();
 
         // Pretend that passwords have been serialized to go directly to the intent.
-        mHandler.getExportCallback().onResult("serialized passwords");
+        mHandler.getExportCallback().onResult(new byte[] {1, 2, 3});
 
         // Before triggering the sharing intent chooser, stub it out to avoid leaving system UI open
         // after the test is finished.
@@ -795,7 +795,7 @@ public class SavePasswordsPreferencesTest {
         });
 
         // Pretend that passwords have been serialized to go directly to the intent.
-        mHandler.getExportCallback().onResult("serialized passwords");
+        mHandler.getExportCallback().onResult(new byte[] {1, 2, 3});
 
         // Before triggering the sharing intent chooser, stub it out to avoid leaving system UI open
         // after the test is finished.
@@ -1006,7 +1006,7 @@ public class SavePasswordsPreferencesTest {
                 .check(matches(isDisplayed()));
 
         // Now pretend that passwords have been serialized.
-        mHandler.getExportCallback().onResult("serialized passwords");
+        mHandler.getExportCallback().onResult(new byte[] {1, 2, 3});
 
         // After simulating the serialized passwords being received, check that the progress bar is
         // hidden.

chrome/browser/android/password_ui_view_android.cc

@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include "base/android/callback_android.h"
+#include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
@@ -213,7 +214,11 @@ void PasswordUIViewAndroid::PostSerializedPasswords(
       } else {
         JNIEnv* env = base::android::AttachCurrentThread();
         base::android::RunCallbackAndroid(
-            callback, ConvertUTF8ToJavaString(env, serialized_passwords));
+            callback,
+            base::android::ToJavaByteArray(
+                env,
+                reinterpret_cast<const uint8_t*>(serialized_passwords.data()),
+                serialized_passwords.size()));
       }
       break;
     }