Add "previewing on hover" support for single-field autocomplete input

components/autofill/content/renderer/autofill_agent.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/content/renderer/autofill_agent.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_split.h"
@@ skipping 132 matching lines @@
     IPC_MESSAGE_HANDLER(AutofillMsg_FormDataFilled, OnFormDataFilled)
     IPC_MESSAGE_HANDLER(AutofillMsg_FieldTypePredictionsAvailable,
                         OnFieldTypePredictionsAvailable)
     IPC_MESSAGE_HANDLER(AutofillMsg_SetAutofillActionFill,
                         OnSetAutofillActionFill)
     IPC_MESSAGE_HANDLER(AutofillMsg_ClearForm, OnClearForm)
     IPC_MESSAGE_HANDLER(AutofillMsg_SetAutofillActionPreview,
                         OnSetAutofillActionPreview)
     IPC_MESSAGE_HANDLER(AutofillMsg_ClearPreviewedForm, OnClearPreviewedForm)
     IPC_MESSAGE_HANDLER(AutofillMsg_SetNodeText, OnSetNodeText)
+    IPC_MESSAGE_HANDLER(AutofillMsg_PreviewAutoCompleteNode,
+                        OnPreviewAutoCompleteNode)
     IPC_MESSAGE_HANDLER(AutofillMsg_AcceptDataListSuggestion,
                         OnAcceptDataListSuggestion)
     IPC_MESSAGE_HANDLER(AutofillMsg_AcceptPasswordAutofillSuggestion,
                         OnAcceptPasswordAutofillSuggestion)
     IPC_MESSAGE_HANDLER(AutofillMsg_RequestAutocompleteResult,
                         OnRequestAutocompleteResult)
     IPC_MESSAGE_HANDLER(AutofillMsg_PageShown, OnPageShown)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ skipping 272 matching lines @@
 void AutofillAgent::OnSetAutofillActionPreview() {
   autofill_action_ = AUTOFILL_PREVIEW;
 }
 
 void AutofillAgent::OnClearPreviewedForm() {
   if (!element_.isNull()) {
     if (password_autofill_agent_->DidClearAutofillSelection(element_))
       return;
 
     ClearPreviewedFormWithElement(element_, was_query_node_autofilled_);
+    element_.setSuggestedValue(WebString());

[Ilya Sherman, 2014/02/22 05:59:51]

Hmm, is this line actually necessary?  It seems like
ClearPreviewedFormWithElement() ought to already take care of this.

[ziran.sun, 2014/02/27 15:38:11]

Done.

   } else {
     // TODO(isherman): There seem to be rare cases where this code *is*
     // reachable: see [ http://crbug.com/96321#c6 ].  Ideally we would
     // understand those cases and fix the code to avoid them.  However, so far I
     // have been unable to reproduce such a case locally.  If you hit this
     // NOTREACHED(), please file a bug against me.
     NOTREACHED();
   }
 }
 
 void AutofillAgent::OnSetNodeText(const base::string16& value) {
   SetNodeText(value, &element_);
 }
 
+void AutofillAgent::OnPreviewAutoCompleteNode(const base::string16& value) {
+   PreviewAutoCompleteNode(value, &element_);

[Ilya Sherman, 2014/02/22 05:59:51]

nit: Why not just inline the implementation here?

[ziran.sun, 2014/02/27 15:38:11]

Done.

+}
+
 void AutofillAgent::OnAcceptDataListSuggestion(const base::string16& value) {
   AcceptDataListSuggestion(value);
 }
 
 void AutofillAgent::OnAcceptPasswordAutofillSuggestion(
     const base::string16& username) {
   // We need to make sure this is handled here because the browser process
   // skipped it handling because it believed it would be handled here. If it
   // isn't handled here then the browser logic needs to be updated.
   bool handled = password_autofill_agent_->DidAcceptAutofillSuggestion(
@@ skipping 139 matching lines @@
 
 void AutofillAgent::SetNodeText(const base::string16& value,
                                 blink::WebInputElement* node) {
   did_set_node_text_ = true;
   base::string16 substring = value;
   substring = substring.substr(0, node->maxLength());
 
   node->setEditingValue(substring);
 }
 
+void AutofillAgent::PreviewAutoCompleteNode(const base::string16& value,
+                                            blink::WebInputElement* node) {
+  base::string16 substring = value;
+  substring = substring.substr(0, node->maxLength());
+
+  node->setSuggestedValue(substring);

[Ilya Sherman, 2014/02/22 05:59:51]

You should also set 

  was_query_node_autofilled_ = element_.isAutofilled();

and set the node to have the autofilled appearance while it being previewed.

[Ilya Sherman, 2014/02/22 05:59:51]

Wow, the method you're cribbing from was needlessly verbose.  I'm fixing it in [
https://codereview.chromium.org/176213002 ].  Please update this method
similarly.

[ziran.sun, 2014/02/27 15:38:11]

Done.

+}
+
 void AutofillAgent::HideAutofillUI() {
   if (!element_.isNull())
     OnClearPreviewedForm();
 
   Send(new AutofillHostMsg_HideAutofillUI(routing_id()));
 }
 
 // TODO(isherman): Decide if we want to support non-password autofill with AJAX.
 void AutofillAgent::didAssociateFormControls(
     const blink::WebVector<blink::WebNode>& nodes) {
   for (size_t i = 0; i < nodes.size(); ++i) {
     blink::WebFrame* frame = nodes[i].document().frame();
     // Only monitors dynamic forms created in the top frame. Dynamic forms
     // inserted in iframes are not captured yet.
     if (!frame->parent()) {
       password_autofill_agent_->OnDynamicFormsSeen(frame);
       return;
     }
   }
 }
 
 }  // namespace autofill