Add password manager autocomplete suggestion when a username element in clicked.

components/autofill/content/renderer/password_autofill_agent.h

Index: components/autofill/content/renderer/password_autofill_agent.h
diff --git a/components/autofill/content/renderer/password_autofill_agent.h b/components/autofill/content/renderer/password_autofill_agent.h
index 72ad5b02f1c932188afa3b97b51ecbbbac607f3b..ad69267a4b1ab03c2d479723c22efe577b0f0d41 100644
--- a/components/autofill/content/renderer/password_autofill_agent.h
+++ b/components/autofill/content/renderer/password_autofill_agent.h
@@ -48,9 +48,11 @@ class PasswordAutofillAgent : public content::RenderViewObserver {
   // cleared when the selection changes.  However, this method returns
   // true when |node| is fillable by password Autofill.
   bool DidClearAutofillSelection(const blink::WebNode& node);
-  // Shows an Autofill popup with username suggestions for |element|.
+  // Shows an Autofill popup with username suggestions for |element|. If
+  // |show_all| is |true|, will show all possible suggestions for that element,
+  // otherwise shows suggestions based on current value of |element|.
   // Returns true if any suggestions were shown, false otherwise.
-  bool ShowSuggestions(const blink::WebInputElement& element);
+  bool ShowSuggestions(const blink::WebInputElement& element, bool show_all);
 
   // Called when new form controls are inserted.
   void OnDynamicFormsSeen(blink::WebFrame* frame);
@@ -124,10 +126,12 @@ class PasswordAutofillAgent : public content::RenderViewObserver {
   void GetSuggestions(const PasswordFormFillData& fill_data,
                       const base::string16& input,
                       std::vector<base::string16>* suggestions,
-                      std::vector<base::string16>* realms);
+                      std::vector<base::string16>* realms,
+                      bool show_all);
 
   bool ShowSuggestionPopup(const PasswordFormFillData& fill_data,
-                           const blink::WebInputElement& user_input);
+                           const blink::WebInputElement& user_input,
+                           bool show_all);
 
   // Attempts to fill |username_element| and |password_element| with the
   // |fill_data|.  Will use the data corresponding to the preferred username,