Revert "Cleanup IsArcAppWindow() in ArcWindowDelegateImpl."

This reverts commit ce0157f4.

Reason for revert: This change breaks text input on ARC windows.
Bug: 866784

Original change's description:
> Cleanup IsArcAppWindow() in ArcWindowDelegateImpl.
> 
> Now aura::client::kAppType property is set for an ARC notification
> window. We can use it for check.
> 
> Change-Id: Id27f5ab83492a4c1a517b1350ae1fc30bfbf8fae
> Reviewed-on: https://chromium-review.googlesource.com/1146626
> Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
> Reviewed-by: Yusuke Sato <yusukes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#577422}

TBR=yusukes@chromium.org,yhanada@chromium.org

Change-Id: I9a58768a0ae0d84d13d9943674ed60954a9b39d5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1148120Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577451}

components/arc/ime/arc_ime_service.cc

@@ -31,6 +31,9 @@ namespace arc {
 
 namespace {
 
+constexpr char kArcNotificationAppId[] =
+    "org.chromium.arc.ArcNotificationService";
+
 base::Optional<double> g_override_default_device_scale_factor;
 
 double GetDefaultDeviceScaleFactor() {
@@ -48,10 +51,29 @@ class ArcWindowDelegateImpl : public ArcImeService::ArcWindowDelegate {
 
   ~ArcWindowDelegateImpl() override = default;
 
-  bool IsInArcAppWindow(const aura::Window* window) const override {
-    for (; window; window = window->parent()) {
-      if (IsArcAppWindow(window))
+  bool IsExoWindow(const aura::Window* window) const override {
+    return exo::Surface::AsSurface(window) ||
+           exo::ShellSurface::GetMainSurface(window);
+  }
+
+  bool IsArcWindow(const aura::Window* window) const override {
+    if (!IsExoWindow(window))
+      return false;
+
+    aura::Window* active = exo::WMHelper::GetInstance()->GetActiveWindow();
+    if (!active || !active->Contains(window))
+      return false;
+    // If the ARC app is focused, the active window should be ARC app window.
+    if (IsArcAppWindow(active))
       return true;
+
+    // If the ARC notification is focused, the active window is not ARC app
+    // window. Find an app id set to the window and check if it is the ARC
+    // notification app id.
+    for (; window && window != active; window = window->parent()) {
+      const std::string* app_id = exo::ShellSurface::GetApplicationId(window);
+      if (app_id)
+        return *app_id == kArcNotificationAppId;
     }
     return false;
   }
@@ -180,11 +202,14 @@ void ArcImeService::ReattachInputMethod(aura::Window* old_window,
 // Overridden from aura::EnvObserver:
 
 void ArcImeService::OnWindowInitialized(aura::Window* new_window) {
-  if (arc_window_delegate_->IsInArcAppWindow(new_window) &&
-      !is_focus_observer_installed_) {
+  // Register the focus observer when every exo window is created because an
+  // application id might not be set here yet.
+  if (arc_window_delegate_->IsExoWindow(new_window)) {
+    if (!is_focus_observer_installed_) {
       arc_window_delegate_->RegisterFocusObserver();
       is_focus_observer_installed_ = true;
     }
+  }
 
   // TODO(mash): Support virtual keyboard under MASH. There is no
   // KeyboardController in the browser process under MASH.
@@ -226,7 +251,7 @@ void ArcImeService::OnWindowFocused(aura::Window* gained_focus,
 
   const bool detach = (lost_focus && focused_arc_window_ == lost_focus);
   const bool attach =
-      (gained_focus && arc_window_delegate_->IsInArcAppWindow(gained_focus));
+      (gained_focus && arc_window_delegate_->IsArcWindow(gained_focus));
 
   if (detach) {
     focused_arc_window_->RemoveObserver(this);

components/arc/ime/arc_ime_service.h

@@ -55,9 +55,9 @@ class ArcImeService : public KeyedService,
 
   class ArcWindowDelegate {
    public:
-    virtual ~ArcWindowDelegate() = default;
-    // Check the |window| is a transient child of an ARC window.
-    virtual bool IsInArcAppWindow(const aura::Window* window) const = 0;
+    virtual ~ArcWindowDelegate() {}
+    virtual bool IsExoWindow(const aura::Window* window) const = 0;
+    virtual bool IsArcWindow(const aura::Window* window) const = 0;
     virtual void RegisterFocusObserver() = 0;
     virtual void UnregisterFocusObserver() = 0;
     virtual ui::InputMethod* GetInputMethodForWindow(

components/arc/ime/arc_ime_service_unittest.cc

@@ -124,7 +124,11 @@ class FakeArcWindowDelegate : public ArcImeService::ArcWindowDelegate {
   explicit FakeArcWindowDelegate(ui::InputMethod* input_method)
       : next_id_(0), test_input_method_(input_method) {}
 
-  bool IsInArcAppWindow(const aura::Window* window) const override {
+  bool IsExoWindow(const aura::Window* window) const override {
+    return IsArcWindow(window);
+  }
+
+  bool IsArcWindow(const aura::Window* window) const override {
     return arc_window_id_.count(window->id());
   }