Convert string16 to base::string16 in content.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 544e4c9cfb269e3505e832ec3bf9c80f4d5b42ed..17512f263c2a9fe29376d460b10eec1b871e21c6 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -2105,7 +2105,7 @@ void RenderWidget::OnCandidateWindowHidden() {
 }
 
 void RenderWidget::OnImeSetComposition(
-    const string16& text,
+    const base::string16& text,
     const std::vector<WebCompositionUnderline>& underlines,
     int selection_start, int selection_end) {
   if (!ShouldHandleImeEvent())
@@ -2124,7 +2124,7 @@ void RenderWidget::OnImeSetComposition(
 #endif
 }
 
-void RenderWidget::OnImeConfirmComposition(const string16& text,
+void RenderWidget::OnImeConfirmComposition(const base::string16& text,
                                            const gfx::Range& replacement_range,
                                            bool keep_selection) {
   if (!ShouldHandleImeEvent())