Bug 1474902 - Part 2. Make nsFocusManager::DetermineElementToMoveFocus public. r=NeilDeakin

Actually, there is no public method to get next element/content by tabIndex or
TAB key. So I would like to use GetNextTabbableContent from IMEStateManager.

Differential Revision: https://phabricator.services.mozilla.com/D12884

--HG--
extra : rebase_source : 48fa0bb3cd834e9458ad69be1a08f3f32afd1049
extra : histedit_source : 5ce46db9caf5e970e5ed31c0a9e30bd656242684

dom/base/nsFocusManager.h

@@ -150,6 +150,23 @@ class nsFocusManager final : public nsIFocusManager,
       nsPIDOMWindowOuter* aWindow, SearchRange aSearchRange,
       nsPIDOMWindowOuter** aFocusedWindow);
 
+  /**
+   * Helper function for MoveFocus which determines the next element
+   * to move the focus to and returns it in aNextContent.
+   *
+   * aWindow is the window to adjust the focus within, and aStart is
+   * the element to start navigation from. For tab key navigation,
+   * this should be the currently focused element.
+   *
+   * aType is the type passed to MoveFocus. If aNoParentTraversal is set,
+   * navigation is not done to parent documents and iteration returns to the
+   * beginning (or end) of the starting document.
+   */
+  nsresult DetermineElementToMoveFocus(nsPIDOMWindowOuter* aWindow,
+                                       nsIContent* aStart, int32_t aType,
+                                       bool aNoParentTraversal,
+                                       nsIContent** aNextContent);
+
   /**
    * Returns the content node that focus will be redirected to if aContent was
    * focused. This is used for the special case of certain XUL elements such
@@ -403,23 +420,6 @@ class nsFocusManager final : public nsIFocusManager,
                                 nsIContent** aStartContent,
                                 nsIContent** aEndContent);
 
-  /**
-   * Helper function for MoveFocus which determines the next element
-   * to move the focus to and returns it in aNextContent.
-   *
-   * aWindow is the window to adjust the focus within, and aStart is
-   * the element to start navigation from. For tab key navigation,
-   * this should be the currently focused element.
-   *
-   * aType is the type passed to MoveFocus. If aNoParentTraversal is set,
-   * navigation is not done to parent documents and iteration returns to the
-   * beginning (or end) of the starting document.
-   */
-  nsresult DetermineElementToMoveFocus(nsPIDOMWindowOuter* aWindow,
-                                       nsIContent* aStart, int32_t aType,
-                                       bool aNoParentTraversal,
-                                       nsIContent** aNextContent);
-
   /**
    * Retrieve the next tabbable element in scope owned by aOwner, using
    * focusability and tabindex to determine the tab order.