Add functionality for copying text within form text fields and form combobox text fields

pdf/pdfium/pdfium_page.h

Index: pdf/pdfium/pdfium_page.h
diff --git a/pdf/pdfium/pdfium_page.h b/pdf/pdfium/pdfium_page.h
index acb2e7df3ab76422b05198a5d001c32a4cc277a4..7dfa79c448307e7f844f4f7091dea5ba38a148a6 100644
--- a/pdf/pdfium/pdfium_page.h
+++ b/pdf/pdfium/pdfium_page.h
@@ -51,9 +51,13 @@ class PDFiumPage {
 
   enum Area {
     NONSELECTABLE_AREA,
-    TEXT_AREA,
-    WEBLINK_AREA,  // Area is a hyperlink.
-    DOCLINK_AREA,  // Area is a link to a different part of the same document.
+    TEXT_AREA,       // Area contains regular, selectable text not
+                     // within form fields.
+    WEBLINK_AREA,    // Area is a hyperlink.
+    DOCLINK_AREA,    // Area is a link to a different part of the same
+                     // document.
+    FORM_TEXT_AREA,  // Area is a form text field or form combobox text
+                     // field.
   };
 
   struct LinkTarget {
@@ -73,6 +77,9 @@ class PDFiumPage {
                     int* form_type,
                     LinkTarget* target);
 
+  // Converts a form type to its corresponding Area.
+  static Area FormTypeToArea(int form_type);
+
   // Gets the character at the given index.
   base::char16 GetCharAtIndex(int index);