Removed used of DisplayContent.getReadOnlyWindowList()

Changed the call points to use DisplayContent.forAllWindows() to
get windows on the display.

Test: Existing tests pass.
Change-Id: I6f8bf15ba246fac69c4a496ebb1d9e0b9b6a95a2
diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index 6a625f4..ff39853 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -1400,14 +1400,14 @@
 
     /** Updates the layer assignment of windows on this display. */
     void assignWindowLayers(boolean setLayoutNeeded) {
-        mLayersController.assignWindowLayers(mWindows.getReadOnly());
+        mLayersController.assignWindowLayers(this);
         if (setLayoutNeeded) {
             setLayoutNeeded();
         }
     }
 
     void adjustWallpaperWindows() {
-        if (mWallpaperController.adjustWallpaperWindows(mWindows.getReadOnly())) {
+        if (mWallpaperController.adjustWallpaperWindows(mWindows)) {
             assignWindowLayers(true /*setLayoutNeeded*/);
         }
     }
@@ -2457,14 +2457,6 @@
         }
     }
 
-    ReadOnlyWindowList getReadOnlyWindowList() {
-        return mWindows.getReadOnly();
-    }
-
-    void getWindows(WindowList output) {
-        output.addAll(mWindows);
-    }
-
     // TODO: Super crazy long method that should be broken down...
     boolean applySurfaceChangesTransaction(boolean recoveringMemory) {