arc: Fall back to use scancode if key_code is not available.

The proxy IME in Android sometimes fail to find the appropriate
KeyboardCode for a Android's KEYCODE. The proxy IME uses
ui::VKEY_UNKNOWN for the key event.
However, it's rejected in a validation code and the mojo connection is
closed as a result.
This CL adds a new optional field in KeyEventData struct for a scan code
of a key event.
The field will be used when the proxy IME fails to find the appropriate
KeyboardCode.

Bug: b:174259561
Test: component_unittests
Change-Id: If4cf5514bdb6cc7026964025e42e4ae6bc3e57b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2567141
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833105}

components/arc/mojom/ime.mojom

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Next MinVersion: 16
+// Next MinVersion: 17
 
 module arc.mojom;
 
@@ -54,6 +54,10 @@ struct KeyEventData {
   bool is_control_down;
   bool is_alt_down;
   bool is_capslock_on;
+  // An optional field used if |key_code| is undefined.
+  // It should be one of evdev codes (i.e. KEY_* defines)
+  // in <linux/input-event-codes.h>.
+  [MinVersion=16] uint32 scan_code;
 };
 
 // Next method ID: 8

components/arc/mojom/ime_mojom_traits.cc

@@ -4,6 +4,8 @@
 
 #include "components/arc/mojom/ime_mojom_traits.h"
 
+#include "ui/events/keycodes/dom/dom_code.h"
+#include "ui/events/keycodes/dom/keycode_converter.h"
 #include "ui/events/keycodes/keyboard_code_conversion.h"
 
 namespace mojo {
@@ -16,8 +18,13 @@ bool StructTraits<arc::mojom::KeyEventDataDataView, KeyEventUniquePtr>::Read(
       data.pressed() ? ui::ET_KEY_PRESSED : ui::ET_KEY_RELEASED;
   // TODO(yhanada): Currently we have no way to know the correct keyboard layout
   // here, so assuming US layout. Find a way to get the more precise DomCode.
-  const ui::DomCode dom_code = ui::UsLayoutKeyboardCodeToDomCode(
+  ui::DomCode dom_code = ui::UsLayoutKeyboardCodeToDomCode(
       static_cast<ui::KeyboardCode>(data.key_code()));
+  if (dom_code == ui::DomCode::NONE) {
+    // |data.key_code| doesn't give us a proper DomCode. Let's fall back to
+    // scan_code.
+    dom_code = ui::KeycodeConverter::EvdevCodeToDomCode(data.scan_code());
+  }
 
   int flags = 0;
   if (data.is_shift_down())

components/arc/mojom/ime_mojom_traits.h

@@ -129,6 +129,9 @@ struct StructTraits<arc::mojom::KeyEventDataDataView, KeyEventUniquePtr> {
   static bool is_capslock_on(const KeyEventUniquePtr& key_event) {
     return key_event->IsCapsLockOn();
   }
+  static int32_t scan_code(const KeyEventUniquePtr& key_event) {
+    return key_event->scan_code();
+  }
 
   static bool Read(arc::mojom::KeyEventDataDataView data,
                    KeyEventUniquePtr* out);

components/arc/mojom/ime_mojom_traits_unittest.cc

@@ -4,6 +4,8 @@
 
 #include "components/arc/mojom/ime.mojom.h"
 
+#include <linux/input.h>
+
 #include "mojo/public/cpp/test_support/test_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/events/event.h"
@@ -41,4 +43,16 @@ TEST(KeyEventStructTraitsTest, Convert) {
   }
 }
 
+TEST(KeyEventStructTraitsTest, FallbackToScancode) {
+  auto original = std::make_unique<ui::KeyEvent>(
+      ui::ET_KEY_PRESSED, ui::VKEY_UNKNOWN, ui::DomCode::NONE, ui::EF_NONE);
+  original->set_scan_code(KEY_A);
+  std::unique_ptr<ui::KeyEvent> output;
+  mojo::test::SerializeAndDeserialize<arc::mojom::KeyEventData>(original,
+                                                                output);
+  EXPECT_EQ(original->type(), output->type());
+  EXPECT_EQ(ui::DomCode::US_A, output->code());
+  EXPECT_EQ(ui::VKEY_A, output->key_code());
+}
+
 }  // namespace mojo