Web Share: Show a warning prompt when share is used from incognito.

chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java

Index: chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
index 80ebc63b65b530d71261e8a977b688a36258ec4f..0ecf63c354b1d882bb9b612ad407d175f433e30e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
@@ -364,17 +364,37 @@ public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegat
         }
     }
 
+    /**
+     * Shows an alert dialog prompting the user to leave incognito mode.
+     *
+     * @param activity The {@link Activity} to launch the dialog from.
+     * @param onAccept Will be called when the user chooses to leave incognito.
+     * @param onCancel Will be called when the user declines to leave incognito.
+     */
+    public static void showLeaveIncognitoWarningDialog(Activity activity,
+            final OnClickListener onAccept, final OnCancelListener onCancel) {
+        new AlertDialog.Builder(activity, R.style.AlertDialogTheme)
+            .setTitle(R.string.external_app_leave_incognito_warning_title)
+            .setMessage(R.string.external_app_leave_incognito_warning)
+            .setPositiveButton(R.string.ok, onAccept)
+            .setNegativeButton(R.string.cancel, new OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        onCancel.onCancel(dialog);
+                    }
+                })
+            .setOnCancelListener(onCancel)
+            .show();
+    }
+
     @Override
     public void startIncognitoIntent(final Intent intent, final String referrerUrl,
             final String fallbackUrl, final Tab tab, final boolean needsToCloseTab) {
         Context context = tab.getWindowAndroid().getContext().get();
         if (!(context instanceof Activity)) return;
 
-        Activity activity = (Activity) context;
-        new AlertDialog.Builder(activity, R.style.AlertDialogTheme)
-            .setTitle(R.string.external_app_leave_incognito_warning_title)
-            .setMessage(R.string.external_app_leave_incognito_warning)
-            .setPositiveButton(R.string.ok, new OnClickListener() {
+        showLeaveIncognitoWarningDialog((Activity) context,
+                new OnClickListener() {
                     @Override
                     public void onClick(DialogInterface dialog, int which) {
                         startActivity(intent);
@@ -383,20 +403,13 @@ public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegat
                             closeTab(tab);
                         }
                     }
-                })
-            .setNegativeButton(R.string.cancel, new OnClickListener() {
-                    @Override
-                    public void onClick(DialogInterface dialog, int which) {
-                        loadIntent(intent, referrerUrl, fallbackUrl, tab, needsToCloseTab, true);
-                    }
-                })
-            .setOnCancelListener(new OnCancelListener() {
+                },
+                new OnCancelListener() {
                     @Override
                     public void onCancel(DialogInterface dialog) {
                         loadIntent(intent, referrerUrl, fallbackUrl, tab, needsToCloseTab, true);
                     }
-                })
-            .show();
+                });
     }
 
     @Override