Send a release event for sticky key when scroll direction is changed.

The unexpected behavior change was introduced in crrev.com/2731283004.
After the change, reversing scroll direction disables the sticky key,
but doesn't send a key release event for it.

Bug: 1049492
Test: unit_tests
Change-Id: I2c57e70e7ecb9cf8d12c17cea9d38d45ff00db05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2041211Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Kevin Schoedel <kpschoedel@chromium.org>
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739200}

ash/sticky_keys/sticky_keys_controller.cc

@@ -32,13 +32,20 @@ ui::EventRewriteStatus RewriteUpdate(
     std::unique_ptr<ui::Event>* rewritten_event) {
   if (consumed)
     return ui::EVENT_REWRITE_DISCARD;
+  const bool flags_rewritten = mod_down_flags & ~event.flags();
+
+  // If the flag is not changed and no need to send a release key event.
+  if (!released && !flags_rewritten)
+    return ui::EVENT_REWRITE_CONTINUE;
+
+  *rewritten_event = ui::Event::Clone(event);
   if (mod_down_flags & ~event.flags()) {
-    *rewritten_event = ui::Event::Clone(event);
     (*rewritten_event)->set_flags(event.flags() | mod_down_flags);
-    return released ? ui::EVENT_REWRITE_DISPATCH_ANOTHER
-                    : ui::EVENT_REWRITE_REWRITTEN;
   }
-  return ui::EVENT_REWRITE_CONTINUE;
+
+  if (released)
+    return ui::EVENT_REWRITE_DISPATCH_ANOTHER;
+  return ui::EVENT_REWRITE_REWRITTEN;
 }
 
 }  // namespace

chrome/browser/chromeos/events/event_rewriter_unittest.cc

@@ -3365,6 +3365,61 @@ TEST_F(EventRewriterAshTest, KeyEventRewritingEdgeCases) {
             static_cast<ui::KeyEvent*>(events[0].get())->key_code());
 }
 
+TEST_F(EventRewriterAshTest, ScrollEventDispatchImpl) {
+  std::vector<std::unique_ptr<ui::Event>> events;
+
+  // Test scroll event is correctly modified.
+  SendActivateStickyKeyPattern(ui::VKEY_CONTROL, ui::DomCode::CONTROL_LEFT,
+                               ui::DomKey::CONTROL);
+  PopEvents(&events);
+  gfx::PointF location(0, 0);
+  ui::ScrollEvent scroll(ui::ET_SCROLL, location, location,
+                         ui::EventTimeForNow(), 0 /* flag */, 0 /* x_offset */,
+                         1 /* y_offset */, 0 /* x_offset_ordinal */,
+                         1 /* y_offset_ordinal */, 2 /* finger */);
+  ui::EventDispatchDetails details = Send(&scroll);
+  ASSERT_FALSE(details.dispatcher_destroyed);
+  PopEvents(&events);
+  EXPECT_EQ(1u, events.size());
+  EXPECT_TRUE(events[0]->IsScrollEvent());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_CONTROL_DOWN);
+
+  // Test FLING_START event deactivates the sticky key, but is modified.
+  ui::ScrollEvent fling_start(
+      ui::ET_SCROLL_FLING_START, location, location, ui::EventTimeForNow(),
+      0 /* flag */, 0 /* x_offset */, 0 /* y_offset */,
+      0 /* x_offset_ordinal */, 0 /* y_offset_ordinal */, 2 /* finger */);
+  details = Send(&fling_start);
+  PopEvents(&events);
+  EXPECT_EQ(2u, events.size());
+  EXPECT_TRUE(events[0]->IsScrollEvent());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_CONTROL_DOWN);
+  EXPECT_EQ(ui::ET_KEY_RELEASED, events[1]->type());
+  EXPECT_EQ(ui::VKEY_CONTROL,
+            static_cast<ui::KeyEvent*>(events[1].get())->key_code());
+
+  // Test scroll direction change causes that modifier release event is sent.
+  SendActivateStickyKeyPattern(ui::VKEY_CONTROL, ui::DomCode::CONTROL_LEFT,
+                               ui::DomKey::CONTROL);
+  details = Send(&scroll);
+  ASSERT_FALSE(details.dispatcher_destroyed);
+  PopEvents(&events);
+
+  ui::ScrollEvent scroll2(ui::ET_SCROLL, location, location,
+                          ui::EventTimeForNow(), 0 /* flag */, 0 /* x_offset */,
+                          -1 /* y_offset */, 0 /* x_offset_ordinal */,
+                          -1 /* y_offset_ordinal */, 2 /* finger */);
+  details = Send(&scroll2);
+  ASSERT_FALSE(details.dispatcher_destroyed);
+  PopEvents(&events);
+  EXPECT_EQ(2u, events.size());
+  EXPECT_TRUE(events[0]->IsScrollEvent());
+  EXPECT_FALSE(events[0]->flags() & ui::EF_CONTROL_DOWN);
+  EXPECT_EQ(ui::ET_KEY_RELEASED, events[1]->type());
+  EXPECT_EQ(ui::VKEY_CONTROL,
+            static_cast<ui::KeyEvent*>(events[1].get())->key_code());
+}
+
 class StickyKeysOverlayTest : public EventRewriterAshTest {
  public:
   StickyKeysOverlayTest() : overlay_(NULL) {}