Add getter for display position to SceneOverlay

This patch adds the concept of display priority to SceneOverlays but
does not yet use them. The new method on the interface will determine
the layering of the overlays, removing the need for the various
case-specific "add overlay" methods.

Bug: 1070281
Change-Id: I518f0324fb154a78bc47f01c6256d9fc3abd0c17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354529Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Mei Liang <meiliang@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806353}

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java

@@ -961,4 +961,9 @@ public class OverlayPanel extends OverlayPanelAnimation implements ActivityState
         closePanel(StateChangeReason.BACK_PRESS, true);
         return true;
     }
+
+    @Override
+    public int getPosition() {
+        return Position.FRONT;
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/SceneOverlay.java

@@ -6,18 +6,36 @@ package org.chromium.chrome.browser.compositor.overlays;
 
 import android.graphics.RectF;
 
+import androidx.annotation.IntDef;
+
 import org.chromium.chrome.browser.compositor.LayerTitleCache;
 import org.chromium.chrome.browser.compositor.layouts.components.VirtualView;
 import org.chromium.chrome.browser.compositor.layouts.eventfilter.EventFilter;
 import org.chromium.chrome.browser.compositor.scene_layer.SceneOverlayLayer;
 import org.chromium.ui.resources.ResourceManager;
 
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.List;
 
 /**
  * An interface which positions the actual tabs and adds additional UI to the them.
  */
 public interface SceneOverlay {
+    /** Positioning information for when overlays are added to the tree. */
+    @IntDef({Position.FRONT, Position.DEFAULT, Position.BACK})
+    @Retention(RetentionPolicy.SOURCE)
+    @interface Position {
+        /** The overlay will be one the of front-most layers. */
+        int FRONT = 0;
+
+        /** The overlay will be between the front and back layers in the order it was added. */
+        int DEFAULT = 1;
+
+        /** The overlay will be one of the back-most layers. */
+        int BACK = 2;
+    }
+
     /**
      * Updates and gets a {@link SceneOverlayLayer} that represents an scene overlay.
      *
@@ -81,4 +99,10 @@ public interface SceneOverlay {
      * @return True if this overlay handles tab creation.
      */
     boolean handlesTabCreating();
+
+    /**
+     * @return Where this overlay should be positioned relative to the other overlays.
+     */
+    @Position
+    int getPosition();
 }

chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/strip/StripLayoutHelperManager.java

@@ -507,6 +507,11 @@ public class StripLayoutHelperManager implements SceneOverlay {
         return false;
     }
 
+    @Override
+    public int getPosition() {
+        return Position.BACK;
+    }
+
     private void tabModelSwitched(boolean incognito) {
         if (incognito == mIsIncognito) return;
         mIsIncognito = incognito;

chrome/android/java/src/org/chromium/chrome/browser/compositor/overlays/toolbar/TopToolbarOverlayCoordinator.java

@@ -111,4 +111,9 @@ public class TopToolbarOverlayCoordinator implements SceneOverlay {
     public boolean handlesTabCreating() {
         return false;
     }
+
+    @Override
+    public int getPosition() {
+        return Position.BACK;
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ScrollingBottomViewSceneLayer.java

@@ -158,6 +158,11 @@ public class ScrollingBottomViewSceneLayer extends SceneOverlayLayer implements
     @Override
     public void getVirtualViews(List<VirtualView> views) {}
 
+    @Override
+    public int getPosition() {
+        return Position.DEFAULT;
+    }
+
     @NativeMethods
     interface Natives {
         long init(ScrollingBottomViewSceneLayer caller);

chrome/android/java/src/org/chromium/chrome/browser/gesturenav/OverscrollGlowOverlay.java

@@ -117,4 +117,9 @@ class OverscrollGlowOverlay extends NavigationGlow implements SceneOverlay {
     public boolean handlesTabCreating() {
         return false;
     }
+
+    @Override
+    public int getPosition() {
+        return Position.BACK;
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/status_indicator/StatusIndicatorSceneLayer.java

@@ -121,6 +121,11 @@ class StatusIndicatorSceneLayer extends SceneOverlayLayer implements SceneOverla
     @Override
     public void getVirtualViews(List<VirtualView> views) {}
 
+    @Override
+    public int getPosition() {
+        return Position.DEFAULT;
+    }
+
     @NativeMethods
     interface Natives {
         long init(StatusIndicatorSceneLayer caller);