capture mode: do not update cursor if we're in cursor updating process.

It's possible that CursorSetter::UpdateCursor() can be called nested so
the cursor can be locked more than once. Do not allow update cursor if
we're in cursor updating process.

Bug: 1152945
Change-Id: I11d3361abf5322f180e9293cb6647490d19380af
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2569980
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833008}

ash/capture_mode/capture_mode_session.cc

@@ -271,6 +271,10 @@ class CaptureModeSession::CursorSetter {
     if (original_cursor_locked_)
       return;
 
+    if (in_cursor_update_)
+      return;
+
+    base::AutoReset<bool> auto_reset_in_cursor_update(&in_cursor_update_, true);
     const ui::mojom::CursorType current_cursor_type =
         cursor_manager_->GetCursor().type();
     const ui::mojom::CursorType new_cursor_type = cursor.type();
@@ -365,6 +369,11 @@ class CaptureModeSession::CursorSetter {
   // True if the cursor has reset back to its original cursor. It's to prevent
   // Reset() from setting the cursor to |original_cursor_| more than once.
   bool was_cursor_reset_to_original_ = true;
+
+  // True if the cursor is currently being updated. This is to prevent
+  // UpdateCursor() is called nestly more than once and the mouse is locked
+  // multiple times.
+  bool in_cursor_update_ = false;
 };
 
 CaptureModeSession::CaptureModeSession(CaptureModeController* controller)

ash/capture_mode/capture_mode_unittests.cc

@@ -1048,6 +1048,26 @@ TEST_F(CaptureModeTest, RegionCursorStates) {
   event_generator->MoveMouseTo(gfx::Point(50, 50));
   EXPECT_EQ(CursorType::kCell, cursor_manager->GetCursor().type());
 
+  // Enter tablet mode, the cursor should be hidden.
+  TabletModeControllerTestApi tablet_mode_controller_test_api;
+  // To avoid flaky failures due to mouse devices blocking entering tablet mode,
+  // we detach all mouse devices. This shouldn't affect testing the cursor
+  // status.
+  tablet_mode_controller_test_api.DetachAllMice();
+  tablet_mode_controller_test_api.EnterTabletMode();
+  EXPECT_FALSE(cursor_manager->IsCursorVisible());
+  EXPECT_TRUE(cursor_manager->IsCursorLocked());
+
+  // Move mouse but it should still be invisible.
+  event_generator->MoveMouseTo(gfx::Point(100, 100));
+  EXPECT_FALSE(cursor_manager->IsCursorVisible());
+  EXPECT_TRUE(cursor_manager->IsCursorLocked());
+
+  // Return to clamshell mode, mouse should appear again.
+  tablet_mode_controller_test_api.LeaveTabletMode();
+  EXPECT_TRUE(cursor_manager->IsCursorVisible());
+  EXPECT_EQ(CursorType::kCell, cursor_manager->GetCursor().type());
+
   // Tests that when exiting capture mode that the cursor is restored to its
   // original state.
   controller->Stop();