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

ui/gfx/canvas_unittest.cc

Index: ui/gfx/canvas_unittest.cc
diff --git a/ui/gfx/canvas_unittest.cc b/ui/gfx/canvas_unittest.cc
index 43ad7f3e71ce913f4756ebceca06ac4dc6abb121..21b9f51e57e8eee4e12e16d4390d83b4c5cbde64 100644
--- a/ui/gfx/canvas_unittest.cc
+++ b/ui/gfx/canvas_unittest.cc
@@ -18,9 +18,10 @@ class CanvasTest : public testing::Test {
   }
 
   gfx::Size SizeStringInt(const char *text, int width, int line_height) {
-    string16 text16 = UTF8ToUTF16(text);
+    base::string16 text16 = UTF8ToUTF16(text);
     int height = 0;
-    int flags = (text16.find('\n') != string16::npos) ? Canvas::MULTI_LINE : 0;
+    int flags =
+      (text16.find('\n') != base::string16::npos) ? Canvas::MULTI_LINE : 0;
     Canvas::SizeStringInt(text16, font_, &width, &height, line_height, flags);
     return gfx::Size(width, height);
   }