Fix Caps Lock remapping issue

Changes:
Remove the Caps Lock modifier for key event when Caps Lock key is
remapped to another key.

BUG=782572
TEST=EventRewriterTest.TestRewriteCapsLock

Change-Id: I561931034acb94719750f9c70f7b8feb6cee5219
Reviewed-on: https://chromium-review.googlesource.com/759816Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515436}

chrome/browser/chromeos/events/event_rewriter_unittest.cc

@@ -1061,6 +1061,44 @@ TEST_F(EventRewriterTest, TestRewriteCapsLock) {
                                       ui::VKEY_F16, ui::DomCode::F16,
                                       ui::EF_MOD3_DOWN, ui::DomKey::F16));
   EXPECT_TRUE(ime_keyboard.caps_lock_is_enabled_);
+
+  // Remap Caps Lock to Control.
+  IntegerPrefMember caps_lock;
+  InitModifierKeyPref(&caps_lock, prefs::kLanguageRemapCapsLockKeyTo,
+                      ui::chromeos::ModifierKey::kControlKey);
+
+  // Press Caps Lock.
+  EXPECT_EQ(GetExpectedResultAsString(ui::ET_KEY_PRESSED, ui::VKEY_CONTROL,
+                                      ui::DomCode::CONTROL_LEFT,
+                                      ui::EF_CONTROL_DOWN, ui::DomKey::CONTROL),
+            GetRewrittenEventAsString(rewriter_, ui::ET_KEY_PRESSED,
+                                      ui::VKEY_CAPITAL, ui::DomCode::CAPS_LOCK,
+                                      ui::EF_CAPS_LOCK_ON | ui::EF_MOD3_DOWN,
+                                      ui::DomKey::CAPS_LOCK));
+
+  // Release Caps Lock.
+  EXPECT_EQ(GetExpectedResultAsString(ui::ET_KEY_RELEASED, ui::VKEY_CONTROL,
+                                      ui::DomCode::CONTROL_LEFT, ui::EF_NONE,
+                                      ui::DomKey::CONTROL),
+            GetRewrittenEventAsString(rewriter_, ui::ET_KEY_RELEASED,
+                                      ui::VKEY_CAPITAL, ui::DomCode::CAPS_LOCK,
+                                      ui::EF_NONE, ui::DomKey::CAPS_LOCK));
+
+  // Press F16.
+  EXPECT_EQ(GetExpectedResultAsString(ui::ET_KEY_PRESSED, ui::VKEY_CONTROL,
+                                      ui::DomCode::CONTROL_LEFT,
+                                      ui::EF_CONTROL_DOWN, ui::DomKey::CONTROL),
+            GetRewrittenEventAsString(rewriter_, ui::ET_KEY_PRESSED,
+                                      ui::VKEY_F16, ui::DomCode::F16,
+                                      ui::EF_MOD3_DOWN, ui::DomKey::F16));
+
+  // Release F16.
+  EXPECT_EQ(GetExpectedResultAsString(ui::ET_KEY_RELEASED, ui::VKEY_CONTROL,
+                                      ui::DomCode::CONTROL_LEFT, ui::EF_NONE,
+                                      ui::DomKey::CONTROL),
+            GetRewrittenEventAsString(rewriter_, ui::ET_KEY_RELEASED,
+                                      ui::VKEY_F16, ui::DomCode::F16,
+                                      ui::EF_MOD3_DOWN, ui::DomKey::F16));
 }
 
 TEST_F(EventRewriterTest, TestRewriteDiamondKey) {

ui/chromeos/events/event_rewriter_chromeos.cc

@@ -767,6 +767,15 @@ bool EventRewriterChromeOS::RewriteModifierKeys(const ui::KeyEvent& key_event,
     state->key = remapped_key->result.key;
     incoming.flags |= characteristic_flag;
     characteristic_flag = remapped_key->flag;
+    if (incoming.key_code == ui::VKEY_CAPITAL ||
+        incoming.key_code == ui::VKEY_F16) {
+      // Caps Lock is rewritten to another key event, remove EF_CAPS_LOCK_ON
+      // flag to prevent the keyboard's Caps Lock state being synced to the
+      // rewritten key event's flag in InputMethodChromeOS. (Caps Lock key on an
+      // external keyboard generates F16 which is treated as Caps Lock and then
+      // rewritten.)
+      incoming.flags &= ~ui::EF_CAPS_LOCK_ON;
+    }
     if (remapped_key->remap_to == ui::chromeos::ModifierKey::kCapsLockKey)
       characteristic_flag |= ui::EF_CAPS_LOCK_ON;
     state->code = RelocateModifier(