chromeos: Enable RenderTextHarfBuzz.

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index bf98bc0cde55524f3fba35a8657a9f3bf99e8600..3b6cf09043bdc1e4e50547776b0a55cd676f9000 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -396,13 +396,22 @@ RenderText* RenderText::CreateInstance() {
 #if defined(OS_MACOSX) && defined(TOOLKIT_VIEWS)
   // Use the more complete HarfBuzz implementation for Views controls on Mac.
   return new RenderTextHarfBuzz;
+#endif
+
+#if defined(OS_LINUX)

[msw, 2014/10/07 18:29:01]

nit: elif?

[Daniel Erat, 2014/10/08 02:03:43]

sure, done

+  // RenderTextPango has severe performance issues (http://crbug.com/376077), so
+  // default to RenderTextHarfBuzz on Linux (and Chrome OS).
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableHarfBuzzRenderText)) {
+    return new RenderTextHarfBuzz;
+  }
 #else
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableHarfBuzzRenderText)) {
     return new RenderTextHarfBuzz;
   }
-  return CreateNativeInstance();
 #endif
+  return CreateNativeInstance();

[msw, 2014/10/07 18:29:01]

nit q: will this trigger unreachable code warnings on Mac Views builds?

[Daniel Erat, 2014/10/08 02:03:43]

good point. i think that nested ifdefs are pretty hard to read, so i'm hopeful
that this works, but i'll change it if it doesn't.

 }
 
 void RenderText::SetText(const base::string16& text) {