Do not log unnecessary message in IsDisplayIdValid

There is still a few cases it prints the warning when
it shouldn't. (in mirroring display scenario)
I'll address it in next CL.

Bug: None
Change-Id: Id254aab0788ab19f6ff970f495be98c7a0ee6e32
Reviewed-on: https://chromium-review.googlesource.com/c/1352032Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612944}

ash/display/persistent_window_controller.cc

@@ -101,10 +101,11 @@ void PersistentWindowController::MaybeRestorePersistentWindowBounds() {
     const int64_t persistent_display_id = persistent_window_info.display_id;
     if (persistent_display_id == screen->GetDisplayNearestWindow(window).id())
       continue;
-    const auto& display =
-        GetDisplayManager()->GetDisplayForId(persistent_display_id);
-    if (!display.is_valid())
+    auto* display_manager = GetDisplayManager();
+    if (!display_manager->IsDisplayIdValid(persistent_display_id))
       continue;
+    const auto& display =
+        display_manager->GetDisplayForId(persistent_display_id);
 
     // Update |persistent_window_bounds| based on |persistent_display_bounds|'s
     // position change. This ensures that |persistent_window_bounds| is

ui/display/manager/display_manager.cc

@@ -477,13 +477,19 @@ void DisplayManager::SetLayoutForCurrentDisplays(
 }
 
 const Display& DisplayManager::GetDisplayForId(int64_t display_id) const {
-  Display* display =
+  auto* display =
       const_cast<DisplayManager*>(this)->FindDisplayForId(display_id);
+  // TODO(oshima): This happens when windows in unified desktop have
+  // been moved to a normal window. Fix this.
+  if (!display && display_id != kUnifiedDisplayId)
+    DLOG(ERROR) << "Could not find display:" << display_id;
   return display ? *display : GetInvalidDisplay();
 }
 
 bool DisplayManager::IsDisplayIdValid(int64_t display_id) const {
-  return GetDisplayForId(display_id).is_valid();
+  Display* display =
+      const_cast<DisplayManager*>(this)->FindDisplayForId(display_id);
+  return !!display;
 }
 
 const Display& DisplayManager::FindDisplayContainingPoint(
@@ -1994,10 +2000,6 @@ Display* DisplayManager::FindDisplayForId(int64_t id) {
                    [id](const Display& display) { return display.id() == id; });
   if (iter != active_display_list_.end())
     return &(*iter);
-  // TODO(oshima): This happens when windows in unified desktop have
-  // been moved to a normal window. Fix this.
-  if (id != kUnifiedDisplayId)
-    DLOG(ERROR) << "Could not find display:" << id;
   return nullptr;
 }
 

ui/display/manager/display_manager.h

@@ -514,7 +514,8 @@ class DISPLAY_MANAGER_EXPORT DisplayManager
   // Same as above but for Unified Desktop.
   void CreateUnifiedDesktopDisplayInfo(DisplayInfoList* display_info_list);
 
-  Display* FindDisplayForId(int64_t id);
+  // Finds an display for given |display_id|. Returns nullptr if not found.
+  Display* FindDisplayForId(int64_t display_id);
 
   // Add the mirror display's display info if the software based mirroring is in
   // use. This should only be called before UpdateDisplaysWith().