Add supports that allow Autofill to be initiated from textarea field

components/autofill/content/renderer/form_autofill_util.cc

Index: components/autofill/content/renderer/form_autofill_util.cc
diff --git a/components/autofill/content/renderer/form_autofill_util.cc b/components/autofill/content/renderer/form_autofill_util.cc
index e0ed2226c17b7b5416dc5b7371272c87945d85c1..5efea2ec67038cbb7495efb66c36b517667e7e76 100644
--- a/components/autofill/content/renderer/form_autofill_util.cc
+++ b/components/autofill/content/renderer/form_autofill_util.cc
@@ -550,6 +550,12 @@ void FillFormField(const FormFieldData& data,
     if (text_area.value() != data.value) {
       text_area.setValue(data.value);
       text_area.dispatchFormControlChangeEvent();
+      if (is_initiating_node) {
+        int length = text_area.value().length();
+        text_area.setSelectionRange(length, length);
+        // Clear the current IME composition (the underline), if there is one.
+        text_area.document().frame()->unmarkText();
+      }
     }
   } else if (IsSelectElement(*field)) {
     WebSelectElement select_element = field->to<WebSelectElement>();
@@ -592,6 +598,12 @@ void PreviewFormField(const FormFieldData& data,
     WebTextAreaElement textarea = field->to<WebTextAreaElement>();
     textarea.setSuggestedValue(data.value);
     field->setAutofilled(true);
+    if (is_initiating_node) {
+      // Select the part of the text that the user didn't type.
+      textarea.setSelectionRange(
+          textarea.value().length(),
+          textarea.suggestedValue().length());
+    }
   }
 }
 
@@ -785,6 +797,8 @@ void WebFormControlElementToFormField(const WebFormControlElement& element,
         base::i18n::RIGHT_TO_LEFT : base::i18n::LEFT_TO_RIGHT;
   } else if (IsTextAreaElement(element)) {
     // Nothing more to do in this case.
+    field->is_autofilled = element.isAutofilled();
+    field->is_focusable = element.isFocusable();
   } else if (extract_mask & EXTRACT_OPTIONS) {
     // Set option strings on the field if available.
     DCHECK(IsSelectElement(element));
@@ -971,10 +985,10 @@ bool WebFormElementToFormData(
   return true;
 }
 
-bool FindFormAndFieldForInputElement(const WebInputElement& element,
-                                     FormData* form,
-                                     FormFieldData* field,
-                                     RequirementsMask requirements) {
+bool FindFormAndFieldForFormControlElement(const WebFormControlElement& element,
+                                           FormData* form,
+                                           FormFieldData* field,
+                                           RequirementsMask requirements) {
   if (!IsAutofillableElement(element))
     return false;
 
@@ -992,7 +1006,7 @@ bool FindFormAndFieldForInputElement(const WebInputElement& element,
                                   field);
 }
 
-void FillForm(const FormData& form, const WebInputElement& element) {
+void FillForm(const FormData& form, const WebFormControlElement& element) {
   WebFormElement form_element = element.form();
   if (form_element.isNull())
     return;
@@ -1033,7 +1047,7 @@ void FillFormForAllElements(const FormData& form_data,
                            &FillFormField);
 }
 
-void PreviewForm(const FormData& form, const WebInputElement& element) {
+void PreviewForm(const FormData& form, const WebFormControlElement& element) {
   WebFormElement form_element = element.form();
   if (form_element.isNull())
     return;
@@ -1046,7 +1060,7 @@ void PreviewForm(const FormData& form, const WebInputElement& element) {
                            &PreviewFormField);
 }
 
-bool ClearPreviewedFormWithElement(const WebInputElement& element,
+bool ClearPreviewedFormWithElement(const WebFormControlElement& element,
                                    bool was_autofilled) {
   WebFormElement form_element = element.form();
   if (form_element.isNull())
@@ -1103,6 +1117,10 @@ bool ClearPreviewedFormWithElement(const WebInputElement& element,
         control_element.setAutofilled(was_autofilled);
       else
         control_element.setAutofilled(false);
+      if (is_initiating_node) {
+        int length = text_area.value().length();
+        text_area.setSelectionRange(length, length);
+      }
     }
   }
 
@@ -1179,7 +1197,7 @@ bool IsWebElementEmpty(const blink::WebElement& element) {
   return true;
 }
 
-gfx::RectF GetScaledBoundingBox(float scale, WebInputElement* element) {
+gfx::RectF GetScaledBoundingBox(float scale, WebFormControlElement* element) {
   gfx::Rect bounding_box(element->boundsInViewportSpace());
   return gfx::RectF(bounding_box.x() * scale,
                     bounding_box.y() * scale,