[Autofill/Autocomplete Feature] Substring matching instead of prefix matching.

components/autofill/content/renderer/form_autofill_util.h

Index: components/autofill/content/renderer/form_autofill_util.h
diff --git a/components/autofill/content/renderer/form_autofill_util.h b/components/autofill/content/renderer/form_autofill_util.h
index 1be05cdac08433fab3baf5dd2e293ea3d2af413c..bc78c49c7af7e6c2da0650a86f6b7701ebe12c67 100644
--- a/components/autofill/content/renderer/form_autofill_util.h
+++ b/components/autofill/content/renderer/form_autofill_util.h
@@ -176,6 +176,12 @@ bool IsWebElementEmpty(const blink::WebElement& element);
 // Return a gfx::RectF that is the bounding box for |element| scaled by |scale|.
 gfx::RectF GetScaledBoundingBox(float scale, blink::WebElement* element);
 
+// Previews the |input_element| with supplied |suggestion| and |user_input|.
+// |input_element| should not be null.
+void PreviewSuggestion(const base::string16& suggestion,
+                       const base::string16& user_input,
+                       blink::WebFormControlElement* input_element);
+
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CONTENT_RENDERER_FORM_AUTOFILL_UTIL_H_