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

pdf/pdfium/pdfium_page.cc

Index: pdf/pdfium/pdfium_page.cc
diff --git a/pdf/pdfium/pdfium_page.cc b/pdf/pdfium/pdfium_page.cc
index 7d85d36aa315e5447995c168c4e4a86caf7a9d5d..36d8e12103d3e9a9b2c3bdaed53d0147932459c4 100644
--- a/pdf/pdfium/pdfium_page.cc
+++ b/pdf/pdfium/pdfium_page.cc
@@ -264,6 +264,10 @@ PDFiumPage::Area PDFiumPage::GetCharIndex(const pp::Point& point,
     DCHECK_NE(control_z_order, link_z_order);
     if (control_z_order > link_z_order) {
       *form_type = control;
+
+      if (*form_type == FPDF_FORMFIELD_TEXTFIELD) {
+        return PDFiumPage::FORM_TEXT_AREA;
+      }
       return PDFiumPage::NONSELECTABLE_AREA;
     }
 
@@ -283,6 +287,11 @@ PDFiumPage::Area PDFiumPage::GetCharIndex(const pp::Point& point,
       return area;
   } else if (control > FPDF_FORMFIELD_UNKNOWN) {
     *form_type = control;
+
+    // TODO(drgage): add in case for combobox later
+    if (*form_type == FPDF_FORMFIELD_TEXTFIELD) {
+      return PDFiumPage::FORM_TEXT_AREA;
+    }
     return PDFiumPage::NONSELECTABLE_AREA;
   }