ui/gfx: Use base::string16 now that string16 was moved into base namespace.

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 ba332d5cac3aa371246b845ea42987495551f4cb..26c32ec95c2e08ddb7af686dc2488968125aa9ac 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -304,7 +304,7 @@ void StyleIterator::UpdatePosition(size_t position) {
 RenderText::~RenderText() {
 }
 
-void RenderText::SetText(const string16& text) {
+void RenderText::SetText(const base::string16& text) {
   DCHECK(!composition_range_.IsValid());
   text_ = text;
 
@@ -797,7 +797,7 @@ void RenderText::SetSelectionModel(const SelectionModel& model) {
   cached_bounds_and_offset_valid_ = false;
 }
 
-const string16& RenderText::GetLayoutText() const {
+const base::string16& RenderText::GetLayoutText() const {
   return obscured() ? obscured_text_ : text();
 }