Implement a modal permission dialog on Android gated by a feature.

chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java b/chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java
new file mode 100644
index 0000000000000000000000000000000000000000..2ebd1f03349e5cdd82927b33bb54aacc7d3d1dbd
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/permissions/PermissionDialogController.java
@@ -0,0 +1,187 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.permissions;
+
+import android.app.Activity;
+import android.content.DialogInterface;
+import android.support.v7.app.AlertDialog;
+import android.support.v7.widget.SwitchCompat;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+import android.text.TextUtils;
+import android.text.method.LinkMovementMethod;
+import android.text.style.ClickableSpan;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.TextView;
+
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.chrome.R;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Singleton instance which controls the display of modal permission dialogs. This class is lazily
+ * initiated when getInstance() is first called. Implemented like this as modal permission dialogs
+ * are disabled by default.
+ *
+ * Unlike permission infobars, which stack on top of each other, only one permission dialog may be
+ * visible on the screen at once. Any additional request for a modal permissions dialog is queued,
+ * and will be displayed once the user responds to the current dialog.
+ */
+public class PermissionDialogController {
+    private AlertDialog mDialog;
+    private SwitchCompat mSwitchView;
+    private List<PermissionDialogDelegate> mRequestQueue;
+
+    // Static holder to ensure safe initialization of the singleton instance.
+    private static class Holder {
+        private static final PermissionDialogController sInstance =
+                new PermissionDialogController();
+    }
+
+    public static PermissionDialogController getInstance() {
+        return Holder.sInstance;
+    }
+
+    private PermissionDialogController() {
+        mRequestQueue = new LinkedList<>();
+    }
+
+    /**
+     * Called by native code to create a modal permission dialog. The PermissionDialogController
+     * will decide whether the dialog needs to be queued (because another dialog is on the screen)
+     * or whether it can be shown immediately.
+     */
+    @CalledByNative
+    private static void createDialog(PermissionDialogDelegate delegate) {
+        PermissionDialogController.getInstance().queueDialog(delegate);
+    }
+
+    /**
+     * Queues a modal permission dialog for display. If there are currently no dialogs on screen, it
+     * will be displayed immediately. Otherwise, it will be displayed as soon as the user responds
+     * to the current dialog.
+     * @param context  The context to use to get the dialog layout.
+     * @param delegate The wrapper for the native-side permission delegate.
+     */
+    private void queueDialog(PermissionDialogDelegate delegate) {
+        mRequestQueue.add(delegate);
+        scheduleDisplay();
+    }
+
+    private void scheduleDisplay() {
+        if (mDialog == null && !mRequestQueue.isEmpty()) showDialog();
+    }
+
+    @VisibleForTesting
+    public AlertDialog getCurrentDialogForTesting() {
+        return mDialog;
+    }
+
+    /**
+     * Shows the dialog asking the user for a web API permission.
+     */
+    public void showDialog() {
+        if (mRequestQueue.isEmpty()) return;
+
+        final PermissionDialogDelegate delegate = mRequestQueue.remove(0);
+        Activity activity = delegate.getActivity();
+        LayoutInflater inflater = LayoutInflater.from(activity);
+        View view = inflater.inflate(R.layout.permission_dialog, null);
+        AlertDialog.Builder builder = new AlertDialog.Builder(activity, R.style.AlertDialogTheme);
+
+        mDialog = builder.create();
+        mDialog.getDelegate().setHandleNativeActionModesEnabled(false);
+        mDialog.setCanceledOnTouchOutside(false);
+
+        TextView messageTextView = (TextView) view.findViewById(R.id.text);
+        messageTextView.setText(prepareMainMessageString(delegate));
+        messageTextView.setVisibility(View.VISIBLE);
+        messageTextView.announceForAccessibility(delegate.getMessageText());
+        messageTextView.setCompoundDrawablesWithIntrinsicBounds(delegate.getDrawableId(), 0, 0, 0);
+        messageTextView.setMovementMethod(LinkMovementMethod.getInstance());
+
+        mSwitchView = (SwitchCompat) view.findViewById(R.id.permission_dialog_persist_toggle);
+        mSwitchView.setChecked(true);
+        TextView toggleTextView =
+                (TextView) view.findViewById(R.id.permission_dialog_persist_message);
+        if (delegate.shouldShowPersistenceToggle()) {
+            mSwitchView.setVisibility(View.VISIBLE);
+            String toggleMessage =
+                    mDialog.getContext().getString(R.string.permission_prompt_persist_text);
+            toggleTextView.setText(toggleMessage);
+            toggleTextView.setVisibility(View.VISIBLE);
+            toggleTextView.announceForAccessibility(toggleMessage);
+
+        } else {
+            mSwitchView.setVisibility(View.GONE);
+            toggleTextView.setVisibility(View.GONE);
+        }
+
+        mDialog.setView(view);
+
+        // Set the buttons to call the appropriate delegate methods. When the dialog is dismissed,
+        // the delegate's native pointers are freed, and the next queued dialog (if any) is
+        // displayed.
+        mDialog.setButton(DialogInterface.BUTTON_POSITIVE,
+                delegate.getPrimaryButtonText(),
+                new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int id) {
+                        delegate.onAccept(mSwitchView.isChecked());
+                    }
+                });
+
+        mDialog.setButton(DialogInterface.BUTTON_NEGATIVE, delegate.getSecondaryButtonText(),
+                new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int id) {
+                        delegate.onCancel(mSwitchView.isChecked());
+                    }
+                });
+
+        // Called when the dialog is dismissed. Interacting with either button in the dialog will
+        // call this handler after the primary/secondary handler.
+        mDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
+            @Override
+            public void onDismiss(DialogInterface dialog) {
+                mDialog = null;
+                delegate.onDismiss();
+                scheduleDisplay();
+            }
+        });
+
+        mDialog.show();
+    }
+
+    private CharSequence prepareMainMessageString(final PermissionDialogDelegate delegate) {
+        SpannableStringBuilder fullString = new SpannableStringBuilder();
+
+        String messageText = delegate.getMessageText();
+        String linkText = delegate.getLinkText();
+        if (!TextUtils.isEmpty(messageText)) fullString.append(messageText);
+
+        // If the linkText exists, then wrap it in a clickable span and concatenate it with the main
+        // dialog message.
+        if (!TextUtils.isEmpty(linkText)) {
+            if (fullString.length() > 0) fullString.append(" ");
+            int spanStart = fullString.length();
+
+            fullString.append(linkText);
+            fullString.setSpan(new ClickableSpan() {
+                @Override
+                public void onClick(View view) {
+                    delegate.onLinkClicked();
+                    if (mDialog != null) mDialog.dismiss();
+                }
+            }, spanStart, fullString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        }
+
+        return fullString;
+    }
+}