Re-enable ARC IMEs that were auto-disabled when toggling to laptop mode

BUG=879365,845079
TEST=Enable Gboard in tablet mode, toggle to laptop mode, toggle back to
 tablet mode, verify Gboard is usable

Change-Id: I8a6094b54b93c5c246ca13adfb391450bd85b80f
Reviewed-on: https://chromium-review.googlesource.com/1199775Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588412}

chrome/browser/chromeos/arc/input_method_manager/arc_input_method_manager_service.cc

@@ -426,6 +426,7 @@ void ArcInputMethodManagerService::SetArcIMEAllowed(bool allowed) {
                           installed_extensions.end());
   }
 
+  std::vector<std::string> ime_ids_to_enable;
   if (allowed) {
     if (!allowed_method_ids_set.empty()) {
       // Some IMEs are not allowed now. Add ARC IMEs to
@@ -436,7 +437,15 @@ void ArcInputMethodManagerService::SetArcIMEAllowed(bool allowed) {
       }
     }
 
-    // TODO(yhanada): Re-enable ARC IMEs that was enabled before disallowed.
+    // Re-enable ARC IMEs that were auto-disabled when toggling to laptop mode.
+    const std::string active_ime_ids =
+        profile_->GetPrefs()->GetString(prefs::kLanguageEnabledImes);
+    std::vector<base::StringPiece> active_ime_list = base::SplitStringPiece(
+        active_ime_ids, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+    for (const auto& id : active_ime_list) {
+      if (chromeos::extension_ime_util::IsArcIME(id.as_string()))
+        ime_ids_to_enable.push_back(id.as_string());
+    }
   } else {
     // Disallow Arc IMEs.
     if (allowed_method_ids_set.empty()) {
@@ -459,6 +468,11 @@ void ArcInputMethodManagerService::SetArcIMEAllowed(bool allowed) {
       std::vector<std::string>(allowed_method_ids_set.begin(),
                                allowed_method_ids_set.end()),
       false /* enable_allowed_input_methods */);
+
+  // This has to be called after SetAllowedInputMethods() because enabling an
+  // IME that is disallowed always fails.
+  for (const auto& id : ime_ids_to_enable)
+    manager->GetActiveIMEState()->EnableInputMethod(id);
 }
 
 void ArcInputMethodManagerService::NotifyInputMethodManagerObservers(

chrome/browser/chromeos/arc/input_method_manager/arc_input_method_manager_service_unittest.cc

@@ -64,6 +64,12 @@ class TestInputMethodManager : public im::MockInputMethodManager {
       removed_input_method_extensions_.push_back(extension_id);
     }
 
+    bool EnableInputMethod(
+        const std::string& new_active_input_method_id) override {
+      enabled_input_methods_.push_back(new_active_input_method_id);
+      return true;
+    }
+
     void AddActiveInputMethodId(const std::string& ime_id) {
       if (!std::count(active_input_method_ids_.begin(),
                       active_input_method_ids_.end(), ime_id)) {
@@ -109,6 +115,7 @@ class TestInputMethodManager : public im::MockInputMethodManager {
     std::vector<std::tuple<std::string, im::InputMethodDescriptors>>
         added_input_method_extensions_;
     std::vector<std::string> removed_input_method_extensions_;
+    std::vector<std::string> enabled_input_methods_;
 
    protected:
     friend base::RefCounted<InputMethodManager::State>;
@@ -476,6 +483,14 @@ TEST_F(ArcInputMethodManagerServiceTest, AllowArcIMEsOnlyInTabletMode) {
   imm()->state()->AddActiveInputMethodId(component_extension_ime_id);
   imm()->state()->AddActiveInputMethodId(arc_ime_id);
 
+  // Update the prefs because the testee checks them. Note that toggling the
+  // mode never changes the prefs.
+  profile()->GetPrefs()->SetString(
+      prefs::kLanguageEnabledImes,
+      base::StringPrintf("%s,%s,%s", extension_ime_id.c_str(),
+                         component_extension_ime_id.c_str(),
+                         arc_ime_id.c_str()));
+
   // All IMEs are allowed to use.
   EXPECT_TRUE(imm()->state()->IsInputMethodAllowed(extension_ime_id));
   EXPECT_TRUE(imm()->state()->IsInputMethodAllowed(component_extension_ime_id));
@@ -490,6 +505,7 @@ TEST_F(ArcInputMethodManagerServiceTest, AllowArcIMEsOnlyInTabletMode) {
   EXPECT_FALSE(imm()->state()->IsInputMethodAllowed(arc_ime_id));
 
   // Back to tablet mode.
+  EXPECT_TRUE(imm()->state()->enabled_input_methods_.empty());
   ToggleTabletMode(true);
 
   // All IMEs are allowed to use.
@@ -497,6 +513,10 @@ TEST_F(ArcInputMethodManagerServiceTest, AllowArcIMEsOnlyInTabletMode) {
   EXPECT_TRUE(imm()->state()->IsInputMethodAllowed(component_extension_ime_id));
   EXPECT_TRUE(imm()->state()->IsInputMethodAllowed(arc_ime_id));
 
+  // Verify they appear in the CrOS IME menu.
+  ASSERT_EQ(1u, imm()->state()->enabled_input_methods_.size());
+  EXPECT_EQ(arc_ime_id, imm()->state()->enabled_input_methods_[0]);
+
   // Do the same tests again, but with |extension_ime_id| disabled.
   imm()->state()->SetAllowedInputMethods(
       {component_extension_ime_id, arc_ime_id},