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

pdf/pdfium/pdfium_engine.h

Index: pdf/pdfium/pdfium_engine.h
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index 6620c77cb6bad9313550bdb79835ac494e61afdb..0241560fd89a1f4b0670f7528f80cbb25c653e8b 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -318,6 +318,11 @@ class PDFiumEngine : public PDFEngine,
       const PP_PrintSettings_Dev& print_settings);
   void SaveSelectedFormForPrint();
 
+  // Sets plugin's selected text to be selected text in form text field
+  // if available.
+  void SetFormSelectedText(const FPDF_FORMHANDLE& hHandle,
+                           const FPDF_PAGE& page);
+
   // Given a mouse event, returns which page and character location it's closest
   // to.
   PDFiumPage::Area GetCharIndex(const pp::MouseInputEvent& event,
@@ -437,9 +442,12 @@ class PDFiumEngine : public PDFEngine,
   // Common code shared by RotateClockwise() and RotateCounterclockwise().
   void RotateInternal();
 
-  // Setting selection status of document.
+  // Setting text selection status of document.

[Lei Zhang, 2017/06/15 18:11:28]

I don't think most readers would understand form text is not included when they
read this comment. Same with line 655.

[drgage, 2017/06/16 01:49:22]

Done.

   void SetSelecting(bool selecting);
 
+  // Sets status of whether or not focus is in form text field.
+  void SetInFormTextField(bool in_form_text_field);
+
   bool PageIndexInBounds(int index) const;
 
   void ScheduleTouchTimer(const pp::TouchInputEvent& event);
@@ -640,12 +648,16 @@ class PDFiumEngine : public PDFEngine,
   bool defer_page_unload_;
   std::vector<int> deferred_page_unloads_;
 
-  // Used for selection.  There could be more than one range if selection spans
-  // more than one page.
+  // Used for text selection in PDFiumPage::TEXT_AREA areas, not within

[Lei Zhang, 2017/06/15 18:11:28]

Can we use PDFiumPage::TEXT_AREA and PDFiumPage::FORM_TEXT_AREA in this comment?
Or don't refer to the enum values as all and explain in plain English.

[drgage, 2017/06/16 01:49:22]

Done.

+  // form text fields. There could be more than one range if selection
+  // spans more than one page.
   std::vector<PDFiumRange> selection_;
-  // True if we're in the middle of selection.
+  // True if we're in the middle of text selection.
   bool selecting_;
 
+  // True if focus is on form text field.
+  bool in_form_text_field_;
+
   MouseDownState mouse_down_state_;
 
   // Used for searching.