Undo ChromeOS Alt-key mapping for keys that have an identical Search key mapping.

Without this mapping, keys are either injected as Alt+<remapped key> or (in the case
of Backspace) are not injected at all. Since an alternative remapping exists using
the search key, and keyboard shortcuts such as Alt+Up are useful in some contexts,
we undo the mapping. Note that this will make it impossible to type, for example,
Alt+PgUp, even if an external keyboard is plugged in.

BUG=435411

Review URL: https://codereview.chromium.org/1393763005

Cr-Commit-Position: refs/heads/master@{#353809}

1 files changed, 39 insertions, 9 deletions

diff --git a/remoting/client/normalizing_input_filter_cros.cc b/remoting/client/normalizing_input_filter_cros.cc
index 0b97652..8cb2229 100644
--- a/remoting/client/normalizing_input_filter_cros.cc
+++ b/remoting/client/normalizing_input_filter_cros.cc
@@ -17,11 +17,6 @@ static bool IsOsKey(uint32_t code) {
          code == static_cast<uint32_t>(ui::DomCode::OS_RIGHT);
 }
 
-// Returns true for the left-hand Alt key.
-static bool IsLeftAltKey(uint32_t code) {
-  return code == static_cast<uint32_t>(ui::DomCode::ALT_LEFT);
-}
-
 // Returns true for codes generated by EventRewriter::RewriteFunctionKeys().
 static bool IsRewrittenFunctionKey(uint32_t code) {
   return code >= static_cast<uint32_t>(ui::DomCode::F1) &&
@@ -96,6 +91,7 @@ NormalizingInputFilterCros::NormalizingInputFilterCros(
       deferred_key_is_rewriting_(false),
       modifying_key_(0),
       left_alt_is_pressed_(false),
+      right_alt_is_pressed_(false),
       previous_mouse_x_(-1),
       previous_mouse_y_(-1) {
 }
@@ -177,10 +173,17 @@ void NormalizingInputFilterCros::ProcessKeyDown(
       SwitchRewritingKeyToModifying();
   }
 
-  if (IsLeftAltKey(event.usb_keycode()))
+  ui::DomCode dom_code = static_cast<ui::DomCode>(event.usb_keycode());
+  if (dom_code == ui::DomCode::ALT_LEFT) {
     left_alt_is_pressed_ = true;
+  } else if (dom_code == ui::DomCode::ALT_RIGHT) {
+    right_alt_is_pressed_ = true;
+  }
 
-  InputFilter::InjectKeyEvent(event);
+  protocol::KeyEvent updated_event = event;
+  UndoAltKeyMapping(&updated_event);
+
+  InputFilter::InjectKeyEvent(updated_event);
 }
 
 void NormalizingInputFilterCros::ProcessKeyUp(const protocol::KeyEvent& event) {
@@ -199,10 +202,17 @@ void NormalizingInputFilterCros::ProcessKeyUp(const protocol::KeyEvent& event) {
   if (modifying_key_ == event.usb_keycode())
     modifying_key_ = 0;
 
-  if (IsLeftAltKey(event.usb_keycode()))
+  ui::DomCode dom_code = static_cast<ui::DomCode>(event.usb_keycode());
+  if (dom_code == ui::DomCode::ALT_LEFT) {
     left_alt_is_pressed_ = false;
+  } else if (dom_code == ui::DomCode::ALT_RIGHT) {
+    right_alt_is_pressed_ = false;
+  }
+
+  protocol::KeyEvent updated_event = event;
+  UndoAltKeyMapping(&updated_event);
 
-  InputFilter::InjectKeyEvent(event);
+  InputFilter::InjectKeyEvent(updated_event);
 }
 
 void NormalizingInputFilterCros::SwitchRewritingKeyToModifying() {
@@ -212,4 +222,24 @@ void NormalizingInputFilterCros::SwitchRewritingKeyToModifying() {
   deferred_keydown_event_ = protocol::KeyEvent();
 }
 
+void NormalizingInputFilterCros::UndoAltKeyMapping(protocol::KeyEvent* event) {
+  if (!left_alt_is_pressed_ && !right_alt_is_pressed_) {
+    return;
+  }
+
+  // If the keycode is one for which the Alt and Search keyboard shortcuts are
+  // the same, map it back to the original key.
+  switch (event->usb_keycode()) {
+    case static_cast<uint32_t>(ui::DomCode::PAGE_DOWN):
+      event->set_usb_keycode(static_cast<uint32_t>(ui::DomCode::ARROW_DOWN));
+      break;
+    case static_cast<uint32_t>(ui::DomCode::PAGE_UP):
+      event->set_usb_keycode(static_cast<uint32_t>(ui::DomCode::ARROW_UP));
+      break;
+    case static_cast<uint32_t>(ui::DomCode::DEL):
+      event->set_usb_keycode(static_cast<uint32_t>(ui::DomCode::BACKSPACE));
+      break;
+  }
+}
+
 }  // namespace remoting