diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index db1c342..ee1e1f6 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -934,7 +934,8 @@
     template <typename Predicate>
     sp<DisplayDevice> findDisplay(Predicate p) const REQUIRES(mStateLock) {
         const auto it = std::find_if(mDisplays.begin(), mDisplays.end(),
-                                     [&](const auto& pair) { return p(*pair.second); });
+                                     [&](const auto& pair)
+                                             REQUIRES(mStateLock) { return p(*pair.second); });
 
         return it == mDisplays.end() ? nullptr : it->second;
     }
@@ -1047,6 +1048,9 @@
     VirtualDisplayId acquireVirtualDisplay(ui::Size, ui::PixelFormat) REQUIRES(mStateLock);
     void releaseVirtualDisplay(VirtualDisplayId);
 
+    // Returns a display other than `mActiveDisplayId` that can be activated, if any.
+    sp<DisplayDevice> getActivatableDisplay() const REQUIRES(mStateLock, kMainThreadContext);
+
     void onActiveDisplayChangedLocked(const DisplayDevice* inactiveDisplayPtr,
                                       const DisplayDevice& activeDisplay)
             REQUIRES(mStateLock, kMainThreadContext);