Clear selection on tabbing to a form text area annotation

If there exists a selection, it should be cleared when we tab to a form
text area annotation.

Add unit tests to validate the scenario.

Bug: 1069465
Change-Id: I8c4f0e70acc0d560a2a45a3c38f43d750ce2a625
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2143783
Commit-Queue: Ankit Kumar 🌪️ <ankk@microsoft.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#765575}

pdf/pdfium/pdfium_engine.cc

@@ -1220,11 +1220,6 @@ bool PDFiumEngine::OnRightMouseDown(const pp::MouseInputEvent& event) {
   // Handle the case when focus starts outside a form text area and transitions
   // into a form text area.
   if (is_form_text_area) {
-    {
-      SelectionChangeInvalidator selection_invalidator(this);
-      selection_.clear();
-    }
-
     FORM_OnFocus(form(), page, 0, page_x, page_y);
     return true;
   }
@@ -3692,6 +3687,10 @@ void PDFiumEngine::OnFocusedAnnotationUpdated(FPDF_ANNOTATION annot) {
   }
   bool is_form_text_area =
       PDFiumPage::FormTypeToArea(form_type) == PDFiumPage::FORM_TEXT_AREA;
+  if (is_form_text_area) {
+    SelectionChangeInvalidator selection_invalidator(this);
+    selection_.clear();
+  }
   SetInFormTextArea(is_form_text_area);
   editable_form_text_area_ =
       is_form_text_area && IsAnnotationAnEditableFormTextArea(annot, form_type);

pdf/pdfium/pdfium_engine_unittest.cc

@@ -259,6 +259,10 @@ class PDFiumEngineTabbingTest : public PDFiumTestBase {
     return engine->in_form_text_area_;
   }
 
+  size_t GetSelectionSize(PDFiumEngine* engine) {
+    return engine->selection_.size();
+  }
+
  protected:
   base::test::TaskEnvironment task_environment_{
       base::test::TaskEnvironment::TimeSource::MOCK_TIME};
@@ -613,4 +617,51 @@ TEST_F(PDFiumEngineTabbingTest, VerifyFormFieldStatesOnTabbing) {
   EXPECT_FALSE(engine->CanEditText());
 }
 
+TEST_F(PDFiumEngineTabbingTest, ClearSelectionOnFocusInFormTextArea) {
+  TestClient client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("form_text_fields.pdf"));
+  ASSERT_TRUE(engine);
+  ASSERT_EQ(1, engine->GetNumberOfPages());
+
+  EXPECT_EQ(PDFiumEngine::FocusElementType::kNone,
+            GetFocusedElementType(engine.get()));
+  EXPECT_EQ(-1, GetLastFocusedPage(engine.get()));
+
+  // Select all text.
+  engine->SelectAll();
+  EXPECT_EQ(1u, GetSelectionSize(engine.get()));
+
+  // Tab to bring focus to a form text area annotation.
+  ASSERT_TRUE(HandleTabEvent(engine.get(), 0));
+  ASSERT_TRUE(HandleTabEvent(engine.get(), 0));
+  EXPECT_EQ(PDFiumEngine::FocusElementType::kPage,
+            GetFocusedElementType(engine.get()));
+  EXPECT_EQ(0, GetLastFocusedPage(engine.get()));
+  EXPECT_EQ(0u, GetSelectionSize(engine.get()));
+}
+
+TEST_F(PDFiumEngineTabbingTest, RetainSelectionOnFocusNotInFormTextArea) {
+  TestClient client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("annots.pdf"));
+  ASSERT_TRUE(engine);
+  ASSERT_EQ(1, engine->GetNumberOfPages());
+
+  EXPECT_EQ(PDFiumEngine::FocusElementType::kNone,
+            GetFocusedElementType(engine.get()));
+  EXPECT_EQ(-1, GetLastFocusedPage(engine.get()));
+
+  // Select all text.
+  engine->SelectAll();
+  EXPECT_EQ(1u, GetSelectionSize(engine.get()));
+
+  // Tab to bring focus to a non form text area annotation (Button).
+  ASSERT_TRUE(HandleTabEvent(engine.get(), PP_INPUTEVENT_MODIFIER_SHIFTKEY));
+  EXPECT_EQ(PDFiumEngine::FocusElementType::kPage,
+            GetFocusedElementType(engine.get()));
+  EXPECT_EQ(0, GetLastFocusedPage(engine.get()));
+  EXPECT_EQ(1u, GetSelectionSize(engine.get()));
+}
+
 }  // namespace chrome_pdf