Reset cursor type when PDF Viewer enters presentation mode

Change PdfViewWebPlugin::HandleSetPresentationModeMessage() to reset the
cursor type when entering presentation mode. This prevents presentation
mode from being stuck with the most recently used cursor, which may be a
cursor used when editing.

Add a test case for HandleSetPresentationModeMessage() to check this
behavior and backfill a missing test to check PDFiumEngine correctly
enters read-only mode. Add some test-only accessors to PdfViewWebPlugin
to support this test.

Bug: 383029258
Change-Id: Ieef1a4b93ef1045c454d4826cf348ffb6b90d6f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6082220
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Andy Phan <andyphan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1395530}

pdf/pdf_view_web_plugin.cc

@@ -1771,7 +1771,12 @@ void PdfViewWebPlugin::HandleSetBackgroundColorMessage(
 
 void PdfViewWebPlugin::HandleSetPresentationModeMessage(
     const base::Value::Dict& message) {
-  engine_->SetReadOnly(message.FindBool("enablePresentationMode").value());
+  const bool presentation_mode =
+      message.FindBool("enablePresentationMode").value();
+  engine_->SetReadOnly(presentation_mode);
+  if (presentation_mode) {
+    cursor_ = ui::mojom::CursorType::kPointer;
+  }
 }
 
 void PdfViewWebPlugin::HandleSetTwoUpViewMessage(

pdf/pdf_view_web_plugin.h

@@ -447,6 +447,11 @@ class PdfViewWebPlugin final : public PDFiumEngineClient,
     return document_load_state_;
   }
 
+  void set_cursor_type_for_testing(ui::mojom::CursorType cursor_type) {
+    cursor_ = cursor_type;
+  }
+  const ui::Cursor& cursor_for_testing() const { return cursor_; }
+
   int GetContentRestrictionsForTesting() const {
     return GetContentRestrictions();
   }

pdf/pdf_view_web_plugin_unittest.cc

@@ -1452,6 +1452,31 @@ TEST_F(PdfViewWebPluginTest, HandleSetBackgroundColorMessage) {
   EXPECT_EQ(SK_ColorGREEN, plugin_->GetBackgroundColor());
 }
 
+TEST_F(PdfViewWebPluginTest, HandleSetPresentationModeMessage) {
+  EXPECT_FALSE(engine_ptr_->IsReadOnly());
+  plugin_->set_cursor_type_for_testing(ui::mojom::CursorType::kIBeam);
+
+  base::Value::Dict message;
+  message.Set("type", "setPresentationMode");
+  message.Set("enablePresentationMode", true);
+  plugin_->OnMessage(message);
+
+  // After entering presentation mode, PDFiumEngine is read-only and the cursor
+  // type has been reset to a pointer.
+  EXPECT_TRUE(engine_ptr_->IsReadOnly());
+  EXPECT_EQ(ui::mojom::CursorType::kPointer,
+            plugin_->cursor_for_testing().type());
+
+  message.Set("enablePresentationMode", false);
+  plugin_->OnMessage(message);
+
+  // After exiting presentation mode, PDFiumEngine is no longer read-only.
+  // The cursor remains as a pointer until the next input event updates it.
+  EXPECT_FALSE(engine_ptr_->IsReadOnly());
+  EXPECT_EQ(ui::mojom::CursorType::kPointer,
+            plugin_->cursor_for_testing().type());
+}
+
 TEST_F(PdfViewWebPluginTest, HandleInputEvent) {
   UpdatePluginGeometryWithoutWaiting(2.0f, {0, 0, 20, 20});