Avoid unnecessary work in |RenderTextWin::UpdateLayout()| if there are no runs.

ui/gfx/render_text_win.cc

Index: ui/gfx/render_text_win.cc
===================================================================
--- ui/gfx/render_text_win.cc	(revision 109436)
+++ ui/gfx/render_text_win.cc	(working copy)
@@ -316,9 +316,11 @@
 void RenderTextWin::UpdateLayout() {
   // TODO(msw): Skip complex processing if ScriptIsComplex returns false.
   ItemizeLogicalText();
-  HDC hdc = CreateCompatibleDC(NULL);
-  LayoutVisualText(hdc);
-  DeleteDC(hdc);
+  if (!runs_.empty()) {
+    HDC hdc = CreateCompatibleDC(NULL);

[sky, 2011/11/10 21:49:04]

nit: use ScopedCreateDC.

[Alexei Svitkine (slow), 2011/11/10 22:10:35]

Done.

+    LayoutVisualText(hdc);
+    DeleteDC(hdc);
+  }
 }
 
 size_t RenderTextWin::IndexOfAdjacentGrapheme(size_t index, bool next) {