Convert string16 to base::string16 in content.

content/browser/renderer_host/test_render_view_host.h

Index: content/browser/renderer_host/test_render_view_host.h
diff --git a/content/browser/renderer_host/test_render_view_host.h b/content/browser/renderer_host/test_render_view_host.h
index 97bcd6e7036b57db1ff75d0a30b920a693ebaab8..680f937784e8c0ccdbb9f1f4e7b78e3c43213d13 100644
--- a/content/browser/renderer_host/test_render_view_host.h
+++ b/content/browser/renderer_host/test_render_view_host.h
@@ -117,7 +117,7 @@ class TestRenderWidgetHostView : public RenderWidgetHostViewBase {
                                  int error_code) OVERRIDE;
   virtual void WillDestroyRenderWidget(RenderWidgetHost* rwh) { }
   virtual void Destroy() OVERRIDE;
-  virtual void SetTooltipText(const string16& tooltip_text) OVERRIDE {}
+  virtual void SetTooltipText(const base::string16& tooltip_text) OVERRIDE {}
   virtual void SelectionBoundsChanged(
       const ViewHostMsg_SelectionBounds_Params& params) OVERRIDE {}
   virtual void ScrollOffsetChanged() OVERRIDE {}
@@ -312,7 +312,7 @@ class TestRenderViewHost
 
   // RenderViewHost overrides --------------------------------------------------
 
-  virtual bool CreateRenderView(const string16& frame_name,
+  virtual bool CreateRenderView(const base::string16& frame_name,
                                 int opener_route_id,
                                 int32 max_page_id) OVERRIDE;
   virtual bool IsRenderViewLive() const OVERRIDE;