Reintroduce password support to NativeTextfieldViews

ui/gfx/render_text_linux.h

Index: ui/gfx/render_text_linux.h
diff --git a/ui/gfx/render_text_linux.h b/ui/gfx/render_text_linux.h
index 79c87b002d2e2494d91860400fa52ae0387b9cfd..066914d7906259226b8fd348661a804ff474f62e 100644
--- a/ui/gfx/render_text_linux.h
+++ b/ui/gfx/render_text_linux.h
@@ -51,17 +51,11 @@ class RenderTextLinux : public RenderText {
   // Returns the run that contains |position|. Return NULL if not found.
   GSList* GetRunContainingPosition(size_t position) const;
 
-  // Given |utf8_index_of_current_grapheme|, returns the UTF-8 index of the
-  // |next| or previous grapheme in logical order. Returns 0 if there is no
-  // previous grapheme, or the |text_| length if there is no next grapheme.
-  size_t Utf8IndexOfAdjacentGrapheme(size_t utf8_index_of_current_grapheme,
-                                     LogicalCursorDirection direction) const;
-
   // Given a |run|, returns the SelectionModel that contains the logical first
   // or last caret position inside (not at a boundary of) the run.
   // The returned value represents a cursor/caret position without a selection.
-  SelectionModel FirstSelectionModelInsideRun(const PangoItem* run) const;
-  SelectionModel LastSelectionModelInsideRun(const PangoItem* run) const;
+  SelectionModel FirstSelectionModelInsideRun(const PangoItem* run);
+  SelectionModel LastSelectionModelInsideRun(const PangoItem* run);
 
   // Unref |layout_| and |pango_line_|. Set them to NULL.
   void ResetLayout();
@@ -75,8 +69,10 @@ class RenderTextLinux : public RenderText {
                             PangoAttribute* pango_attr,
                             PangoAttrList* attrs);
 
-  size_t Utf16IndexToUtf8Index(size_t index) const;
-  size_t Utf8IndexToUtf16Index(size_t index) const;
+  // These functions convert between indices into text() and indices into
+  // layout_text_.

[msw, 2012/02/22 00:33:26]

barify |layout_text_|; consider one-liner:
// Convert between indices into text() and indices into |layout_text_|.

[benrg, 2012/02/24 19:07:44]

Done.

+  size_t TextIndexToLayoutIndex(size_t index) const;
+  size_t LayoutIndexToTextIndex(size_t index) const;
 
   // Calculate the visual bounds containing the logical substring within |from|
   // to |to|.
@@ -103,6 +99,12 @@ class RenderTextLinux : public RenderText {
   // The text length.
   size_t layout_text_len_;
 
+  // Corresponding indices from the last call of |TextIndexToLayoutIndex| or
+  // |LayoutIndexToTextIndex|, cached so that algorithms that call these

[msw, 2012/02/22 00:33:26]

If either of these functions are called consecutively with indices further apart
from one another than from the start of the string, then this has a negative
performance impact, right? I don't like speculating on the severity of
performance impacts, but without more info, I'm dubious that this is worth the
added complexity.

[benrg, 2012/02/22 02:25:43]

Relative to caching offsets within each loop, it's less error prone (there are
fewer chances to get the caching wrong) and it avoids mixing the caching
optimization with whatever the loop is really trying to do. On the other hand
its performance characteristics are not especially transparent, as you said. In
any case, it doesn't need to be in this CL. I think I'll back it out.

+  // functions in a loop are O(n) instead of O(n^2).
+  mutable size_t last_text_index_;
+  mutable const char* last_layout_pointer_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderTextLinux);
 };