aura: removes some dead code from FocusSynchronizer

This code is dead after removing window manager interfaces.

BUG=none
TEST=none

Change-Id: If80370ec29fa97315b54b5404ee1287df36b82ab
Reviewed-on: https://chromium-review.googlesource.com/1153403Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578725}

ui/aura/mus/focus_synchronizer.cc

@@ -44,16 +44,11 @@ void FocusSynchronizer::SetFocusFromServer(WindowMus* window) {
     Window* root = window->GetWindow()->GetRootWindow();
     // The client should provide a focus client for all roots.
     DCHECK(client::GetFocusClient(root));
-    if (is_singleton_focus_client_)
-      DCHECK_EQ(active_focus_client_, client::GetFocusClient(root));
-    else if (active_focus_client_root_ != root)
+    if (active_focus_client_root_ != root)
       SetActiveFocusClient(client::GetFocusClient(root), root);
     window->GetWindow()->Focus();
   } else if (active_focus_client_) {
-    if (is_singleton_focus_client_)
-      active_focus_client_->FocusWindow(nullptr);
-    else
-      SetActiveFocusClient(nullptr, nullptr);
+    SetActiveFocusClient(nullptr, nullptr);
   }
 }
 
@@ -61,13 +56,6 @@ void FocusSynchronizer::OnFocusedWindowDestroyed() {
   focused_window_ = nullptr;
 }
 
-void FocusSynchronizer::SetSingletonFocusClient(
-    client::FocusClient* focus_client) {
-  SetActiveFocusClient(focus_client, nullptr);
-  if (focus_client)
-    is_singleton_focus_client_ = true;
-}
-
 void FocusSynchronizer::SetActiveFocusClient(client::FocusClient* focus_client,
                                              Window* focus_client_root) {
   if (focus_client == active_focus_client_ &&
@@ -75,8 +63,6 @@ void FocusSynchronizer::SetActiveFocusClient(client::FocusClient* focus_client,
     return;
   }
 
-  is_singleton_focus_client_ = false;
-
   if (active_focus_client_root_)
     active_focus_client_root_->RemoveObserver(this);
   active_focus_client_root_ = focus_client_root;
@@ -137,14 +123,12 @@ void FocusSynchronizer::OnWindowFocused(Window* gained_focus,
 }
 
 void FocusSynchronizer::OnWindowDestroying(Window* window) {
-  DCHECK(!is_singleton_focus_client_);
   SetActiveFocusClient(nullptr, nullptr);
 }
 
 void FocusSynchronizer::OnWindowPropertyChanged(Window* window,
                                                 const void* key,
                                                 intptr_t old) {
-  DCHECK(!is_singleton_focus_client_);
   if (key != client::kFocusClientKey)
     return;
 

ui/aura/mus/focus_synchronizer.h

@@ -28,12 +28,7 @@ class FocusClient;
 }
 
 // FocusSynchronizer is responsible for keeping focus in sync between aura
-// and the mus server. FocusSynchronizer may be configured in two distinct
-// ways:
-// . SetSingletonFocusClient(). Use this when a single FocusClient is shared
-//   among all windows and never changes.
-// . SetActiveFocusClient(). Use this when there may be more than one
-//   FocusClient.
+// and the mus server.
 class AURA_EXPORT FocusSynchronizer : public client::FocusChangeObserver,
                                       public WindowObserver {
  public:
@@ -56,11 +51,6 @@ class AURA_EXPORT FocusSynchronizer : public client::FocusChangeObserver,
   // Called when the focused window is destroyed.
   void OnFocusedWindowDestroyed();
 
-  // Used when the focus client is shared among all windows. See class
-  // description for details.
-  void SetSingletonFocusClient(client::FocusClient* focus_client);
-  bool is_singleton_focus_client() const { return is_singleton_focus_client_; }
-
   // Sets the active FocusClient and the window the FocusClient is associated
   // with. |focus_client_root| is not necessarily the window that actually has
   // focus.
@@ -96,8 +86,6 @@ class AURA_EXPORT FocusSynchronizer : public client::FocusChangeObserver,
   bool setting_focus_ = false;
   WindowMus* window_setting_focus_to_ = nullptr;
 
-  bool is_singleton_focus_client_ = false;
-
   client::FocusClient* active_focus_client_ = nullptr;
   // The window that |active_focus_client_| is associated with.
   Window* active_focus_client_root_ = nullptr;