WindowService: Removes EventProcessorDelegate::IsWindowInDisplayRoot

And instead changes GetRootWindowForEventDispatch() to return null if
not in a valid hierarchy for event dispatch.

BUG=none
TEST=none

Change-Id: I9e8d23d3607fb600d2cf0c80ff1086688a4b6c13
Reviewed-on: https://chromium-review.googlesource.com/956849Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542324}

services/ui/ws/event_processor.cc

@@ -845,10 +845,8 @@ void EventProcessor::OnDrawnStateChanged(ServerWindow* ancestor,
 
 void EventProcessor::OnRootDidChange(ServerWindow* ancestor,
                                      ServerWindow* window) {
-  if (delegate_->IsWindowInDisplayRoot(window))
-    return;
-
-  WindowNoLongerValidTarget(window);
+  if (!delegate_->GetRootWindowForEventDispatch(window))
+    WindowNoLongerValidTarget(window);
 }
 
 void EventProcessor::OnDragCursorUpdated() {

services/ui/ws/event_processor.h

@@ -51,7 +51,7 @@ class EventProcessorTestApi;
 }
 
 // Processes events sent to the Window Service from the native platform. Updates
-// internale state associated with events (such as mouse, keyboard state,
+// internal state associated with events (such as mouse, keyboard state,
 // capture, focus...). EventProcessorDelegate handles dispatching to the
 // appropriate client.
 class EventProcessor : public ServerWindowDrawnTrackerObserver,

services/ui/ws/event_processor_delegate.h

@@ -94,14 +94,11 @@ class EventProcessorDelegate {
   virtual ServerWindow* GetRootWindowForDisplay(int64_t display_id) = 0;
 
   // Returns the root of |window| that is used for event dispatch. The returned
-  // value is used for coordinate conversion.
+  // value is used for coordinate conversion. Returns null if |window| is not
+  // in a hierarchy that events should be dispatched to (typically not
+  // associated with a display).
   virtual ServerWindow* GetRootWindowForEventDispatch(ServerWindow* window) = 0;
 
-  // Returns true if |window| is in a display root. This is called when the
-  // hierarchy changes and |window| needs to be tested if it's still in a valid
-  // display root.
-  virtual bool IsWindowInDisplayRoot(const ServerWindow* window) = 0;
-
   // Called when event dispatch could not find a target. OnAccelerator may still
   // be called.
   virtual void OnEventTargetNotFound(const ui::Event& event,

services/ui/ws/event_processor_unittest.cc

@@ -204,10 +204,7 @@ class TestEventProcessorDelegate : public EventProcessorDelegate {
     return nullptr;
   }
   ServerWindow* GetRootWindowForEventDispatch(ServerWindow* window) override {
-    return window->GetRootForDrawn();
-  }
-  bool IsWindowInDisplayRoot(const ServerWindow* window) override {
-    return is_window_in_display_root_;
+    return is_window_in_display_root_ ? window->GetRootForDrawn() : nullptr;
   }
 
   Delegate* delegate_;

services/ui/ws/window_manager_state.cc

@@ -900,20 +900,9 @@ ServerWindow* WindowManagerState::GetRootWindowForEventDispatch(
     if (client_visible_root->Contains(window))
       return client_visible_root;
   }
-  NOTREACHED();
   return nullptr;
 }
 
-bool WindowManagerState::IsWindowInDisplayRoot(const ServerWindow* window) {
-  for (auto& display_root_ptr : window_manager_display_roots_) {
-    ServerWindow* client_visible_root =
-        display_root_ptr->GetClientVisibleRoot();
-    if (client_visible_root->Contains(window))
-      return true;
-  }
-  return false;
-}
-
 void WindowManagerState::OnEventTargetNotFound(const ui::Event& event,
                                                int64_t display_id) {
   window_server()->SendToPointerWatchers(event, nullptr, /* window */

services/ui/ws/window_manager_state.h

@@ -273,7 +273,6 @@ class WindowManagerState : public EventProcessorDelegate,
                                           bool in_nonclient_area) override;
   ServerWindow* GetRootWindowForDisplay(int64_t display_id) override;
   ServerWindow* GetRootWindowForEventDispatch(ServerWindow* window) override;
-  bool IsWindowInDisplayRoot(const ServerWindow* window) override;
   void OnEventTargetNotFound(const Event& event, int64_t display_id) override;
   ServerWindow* GetFallbackTargetForEventBlockedByModal(
       ServerWindow* window) override;