ozone: evdev: Drop unmapped key events

In particular BTN_* events for the touchpad should not be dispatched as
keypresses. So just filter any presses that aren't mapped.

BUG=425617
TEST=manual on link_freon, events_unittests

Review URL: https://codereview.chromium.org/668943003

Cr-Commit-Position: refs/heads/master@{#300559}

ui/events/ozone/evdev/key_event_converter_evdev_unittest.cc

@@ -354,3 +354,18 @@ TEST_F(KeyEventConverterEvdevTest, KeyWithLock) {
   EXPECT_EQ(ui::VKEY_CAPITAL, event->key_code());
   EXPECT_EQ(0, event->flags());
 }
+
+TEST_F(KeyEventConverterEvdevTest, UnmappedKeyPress) {
+  ui::MockKeyEventConverterEvdev* dev = device();
+
+  struct input_event mock_kernel_queue[] = {
+      {{0, 0}, EV_KEY, BTN_TOUCH, 1},
+      {{0, 0}, EV_SYN, SYN_REPORT, 0},
+
+      {{0, 0}, EV_KEY, BTN_TOUCH, 0},
+      {{0, 0}, EV_SYN, SYN_REPORT, 0},
+  };
+
+  dev->ProcessEvents(mock_kernel_queue, arraysize(mock_kernel_queue));
+  EXPECT_EQ(0u, size());
+}

ui/events/ozone/evdev/keyboard_evdev.cc

@@ -228,6 +228,9 @@ void KeyboardEvdev::DispatchKey(unsigned int key, bool down) {
   ui::KeyboardCode code = KeyboardCodeFromEvdevKey(key);
   int flags = modifiers_->GetModifierFlags();
 
+  if (code == VKEY_UNKNOWN)
+    return;
+
   callback_.Run(make_scoped_ptr(new KeyEvent(
       down ? ET_KEY_PRESSED : ET_KEY_RELEASED,
       code,