Fix another discrepancy in text selection between PDF and HTML forms.

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index f71ef7ce71f8b2ccb87dc7e2326c1967ee9fe648..035841b3e273c2344373bac72cbf164dc18a1724 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -1653,8 +1653,10 @@ void PDFiumEngine::SetFormSelectedText(FPDF_FORMHANDLE form_handle,
   // selection has changed. If so, set plugin text selection.
   std::string selected_form_text = selected_form_text_;
   selected_form_text_ = base::UTF16ToUTF8(selected_form_text16);
-  if (selected_form_text != selected_form_text_)
+  if (selected_form_text != selected_form_text_) {
+    DCHECK(in_form_text_area_);
     pp::PDF::SetSelectedText(GetPluginInstance(), selected_form_text_.c_str());
+  }
 }
 
 void PDFiumEngine::PrintEnd() {
@@ -1725,7 +1727,9 @@ bool PDFiumEngine::OnMouseDown(const pp::MouseInputEvent& event) {
 
   SetMouseLeftButtonDown(event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT);
 
-  SelectionChangeInvalidator selection_invalidator(this);
+  std::unique_ptr<chrome_pdf::PDFiumEngine::SelectionChangeInvalidator>

[Lei Zhang, 2017/07/10 23:08:20]

Since the return value from base::MakeUnique() (which will become
std::make_unique() eventually) is well known. You can just replace this long
line with "auto".

[drgage, 2017/07/11 17:25:36]

Done.

+      selection_invalidator =
+          base::MakeUnique<SelectionChangeInvalidator>(this);
   selection_.clear();
 
   int page_index = -1;
@@ -1754,6 +1758,7 @@ bool PDFiumEngine::OnMouseDown(const pp::MouseInputEvent& event) {
     FORM_OnLButtonDown(form_, pages_[page_index]->GetPage(), 0, page_x, page_y);
     if (form_type > FPDF_FORMFIELD_UNKNOWN) {  // returns -1 sometimes...
       mouse_down_state_.Set(PDFiumPage::FormTypeToArea(form_type), target);
+      selection_invalidator.reset();

[Lei Zhang, 2017/07/10 23:08:21]

Can you add a comment to explain why this has to be called here?

[drgage, 2017/07/11 17:25:36]

Done.

 
       bool is_valid_control = (form_type == FPDF_FORMFIELD_TEXTFIELD ||
                                form_type == FPDF_FORMFIELD_COMBOBOX);
@@ -3583,6 +3588,7 @@ void PDFiumEngine::GetRegion(const pp::Point& location,
 }
 
 void PDFiumEngine::OnSelectionChanged() {
+  DCHECK(!in_form_text_area_);
   pp::PDF::SetSelectedText(GetPluginInstance(), GetSelectedText().c_str());
 }
 
@@ -3621,6 +3627,10 @@ void PDFiumEngine::SetSelecting(bool selecting) {
 }
 
 void PDFiumEngine::SetInFormTextArea(bool in_form_text_area) {
+  // If focus previously in form text area, clear form text selection.

[Lei Zhang, 2017/07/10 23:08:20]

// If focus was previously in the form text area, clear the form text selection.
Otherwise ... ?

[drgage, 2017/07/11 17:25:37]

Otherwise, nothing is cleared; the focus is changed and the in_form_text_area_
variable is set (like in the other case). Do you want me to add a comment that
explains this? I didn't think it was necessary because the lines 3634 and 3635
always run.

[Lei Zhang, 2017/07/11 20:37:38]

Otherwise, nothing is cleared and if |in_form_text_area_| flips to false, then
there is no way to clear the renderer clipboard selection. All the
pp::PDF::SetSelectedText() calls while |in_form_text_area_| is false goes to the
MimeHandler.

+  if (in_form_text_area_)
+    pp::PDF::SetSelectedText(GetPluginInstance(), "");
+
   client_->FormTextFieldFocusChange(in_form_text_area);
   in_form_text_area_ = in_form_text_area;
 }