Implement Uniscribe RenderText for Windows.

ui/gfx/render_text.h

Index: ui/gfx/render_text.h
diff --git a/ui/gfx/render_text.h b/ui/gfx/render_text.h
index cc4f4e5f66c280b195058a20f29297a5217229a9..3a69c64ed42e49d12e4ac19743fbeae1de3a1529 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -160,7 +160,7 @@ class UI_EXPORT RenderText {
   void set_cursor_visible(bool visible) { cursor_visible_ = visible; }
 
   bool insert_mode() const { return insert_mode_; }
-  void toggle_insert_mode() { insert_mode_ = !insert_mode_; }
+  void ToggleInsertMode();
 
   bool focused() const { return focused_; }
   void set_focused(bool focused) { focused_ = focused; }
@@ -176,7 +176,7 @@ class UI_EXPORT RenderText {
   // edits take place, and doesn't necessarily correspond to
   // SelectionModel::caret_pos.
   size_t GetCursorPosition() const;
-  void SetCursorPosition(const size_t position);
+  void SetCursorPosition(size_t position);
 
   void SetCaretPlacement(SelectionModel::CaretPlacement placement) {
       selection_model_.set_caret_placement(placement);
@@ -184,7 +184,7 @@ class UI_EXPORT RenderText {
 
   // Moves the cursor left or right. Cursor movement is visual, meaning that
   // left and right are relative to screen, not the directionality of the text.
-  // If |select| is false, the selection range is emptied at the new position.
+  // If |select| is false, the selection start is moved to the same position.
   void MoveCursorLeft(BreakType break_type, bool select);
   void MoveCursorRight(BreakType break_type, bool select);
 
@@ -193,7 +193,8 @@ class UI_EXPORT RenderText {
   bool MoveCursorTo(const SelectionModel& selection);
 
   // Move the cursor to the position associated with the clicked point.
-  // If |select| is false, the selection range is emptied at the new position.
+  // If |select| is false, the selection start is moved to the same position.
+  // Returns true if the cursor position or selection range changed.
   bool MoveCursorTo(const Point& point, bool select);
 
   size_t GetSelectionStart() const {
@@ -289,8 +290,10 @@ class UI_EXPORT RenderText {
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, ApplyStyleRange);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, StyleRangesAdjust);
 
-  // Clear out |style_ranges_|.
-  void ClearStyleRanges();
+  // Set the cursor to |position|, with the caret trailing the previous
+  // grapheme, or if there is no previous grapheme, leading the cursor position.
+  // If |select| is false, the selection start is moved to the same position.
+  void MoveCursorTo(size_t position, bool select);
 
   bool IsPositionAtWordSelectionBoundary(size_t pos);