[TLDD] Added placeholder strategy for drag drop reorder

Bug: 381285152
Change-Id: I6b7aa2645ebf4b7cfaed8d3d44afd3d317d58bf6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6064021
Commit-Queue: Sirisha Kavuluru <[email protected]>
Code-Coverage: [email protected] <[email protected]>
Reviewed-by: Neil Coronado <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1391249}

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

@@ -74,8 +74,9 @@ public class ReorderDelegate {
     private StripLayoutTab mInteractingTab;
 
     private ReorderStrategy mActiveStrategy;
-    private final ReorderTabStrategy mTabStrategy = new ReorderTabStrategy();
-    private final ReorderGroupStrategy mGroupStrategy = new ReorderGroupStrategy();
+    private final TabReorderStrategy mTabStrategy = new TabReorderStrategy();
+    private final GroupReorderStrategy mGroupStrategy = new GroupReorderStrategy();
+    private final DragDropReorderStrategy mDragDropStrategy = new DragDropReorderStrategy();
 
     // Auto-scroll State.
     private long mLastReorderScrollTime;
@@ -125,6 +126,19 @@ void setInteractingTab(StripLayoutTab interactingTab) {
         mInteractingTab = interactingTab;
     }
 
+    private ReorderStrategy getReorderStrategy(
+            StripLayoutView interactingView, boolean isReorderForDrop) {
+        if (isReorderForDrop) {
+            return mDragDropStrategy;
+        } else if (interactingView instanceof StripLayoutTab) {
+            return mTabStrategy;
+        } else if (interactingView instanceof StripLayoutGroupTitle) {
+            return mGroupStrategy;
+        }
+        assert false : "Attempted to start reorder on an unexpected view type: " + interactingView;
+        return null;
+    }
+
     // ============================================================================================
     // Initialization
     // ============================================================================================
@@ -160,28 +174,16 @@ void initialize(
     // Reorder API
     // ============================================================================================
 
-    /**
-     * Begin reordering the interacting view.
-     *
-     * @param stripTabs The list of {@link StripLayoutTab}.
-     * @param interactingView The interacting {@link StripLayoutView}.
-     * @param effectiveTabWidth The width of a tab, accounting for overlap.
-     * @param x The x coordinate that the reorder action began at.
-     */
-    void startReorder(
+    /** See {@link ReorderStrategy#startReorderMode} */
+    void startReorderMode(
             StripLayoutTab[] stripTabs,
             @NonNull StripLayoutView interactingView,
             float effectiveTabWidth,
             float x) {
-        if (interactingView instanceof StripLayoutTab interactingTab) {
-            mTabStrategy.startReorderTab(stripTabs, interactingTab, effectiveTabWidth, x);
-            mActiveStrategy = mTabStrategy;
-        } else if (interactingView instanceof StripLayoutGroupTitle) {
-            mGroupStrategy.startReorderGroup();
-            mActiveStrategy = mGroupStrategy;
-        } else {
-            assert false : "Attempted to start reorder on an unexpected view type.";
-        }
+        assert mActiveStrategy == null && !getInReorderMode();
+        // TODO(crbug.com/381285152): Pass isReorderForDrop as arg.
+        mActiveStrategy = getReorderStrategy(interactingView, /* isReorderForDrop= */ false);
+        mActiveStrategy.startReorderMode(stripTabs, interactingView, effectiveTabWidth, x);
     }
 
     /** See {@link ReorderStrategy#updateReorderPosition} */
@@ -190,13 +192,15 @@ void updateReorderPosition(
             StripLayoutGroupTitle[] groupTitles,
             StripLayoutTab[] stripTabs,
             float deltaX) {
-        assert mActiveStrategy != null : "Attempted to update reorder without an active Strategy.";
+        assert mActiveStrategy != null && getInReorderMode()
+                : "Attempted to update reorder without an active Strategy.";
         mActiveStrategy.updateReorderPosition(stripViews, groupTitles, stripTabs, deltaX);
     }
 
     /** See {@link ReorderStrategy#stopReorderMode} */
     void stopReorderMode(StripLayoutGroupTitle[] groupTitles, StripLayoutTab[] stripTabs) {
-        assert mActiveStrategy != null : "Attempted to stop reorder without an active Strategy.";
+        assert mActiveStrategy != null && getInReorderMode()
+                : "Attempted to stop reorder without an active Strategy.";
         mActiveStrategy.stopReorderMode(groupTitles, stripTabs);
         mActiveStrategy = null;
     }
@@ -341,22 +345,17 @@ private void resetTabGroupMargins(
     // Tab reorder helpers
     // ============================================================================================
 
-    private class ReorderTabStrategy implements ReorderStrategy {
-        /**
-         * Begin reordering the interacting tab.
-         *
-         * @param stripTabs The list of {@link StripLayoutTab}.
-         * @param interactingTab The interacting {@link StripLayoutTab}.
-         * @param effectiveTabWidth The width of a tab, accounting for overlap.
-         * @param x The x coordinate that the reorder action began at.
-         */
-        void startReorderTab(
+    private class TabReorderStrategy implements ReorderStrategy {
+
+        /** See {@link ReorderStrategy#startReorderMode} */
+        @Override
+        public void startReorderMode(
                 StripLayoutTab[] stripTabs,
-                StripLayoutTab interactingTab,
+                StripLayoutView interactingTab,
                 float effectiveTabWidth,
                 float x) {
             RecordUserAction.record("MobileToolbarStartReorderTab");
-            setInteractingTab(interactingTab);
+            setInteractingTab((StripLayoutTab) interactingTab);
 
             // 1. Set reorder mode to true before selecting this tab to prevent unnecessarily
             // triggering #bringSelectedTabToVisibleArea for edge tabs when the tab strip is full.
@@ -711,8 +710,13 @@ private float getHalfTabWidth() {
     // Group reorder helpers
     // ============================================================================================
 
-    private static class ReorderGroupStrategy implements ReorderStrategy {
-        void startReorderGroup() {
+    private static class GroupReorderStrategy implements ReorderStrategy {
+        @Override
+        public void startReorderMode(
+                StripLayoutTab[] stripTabs,
+                @NonNull StripLayoutView interactingView,
+                float effectiveTabWidth,
+                float x) {
             // TODO(crbug.com/376069497): Implement.
         }
 
@@ -743,6 +747,33 @@ void onReorderingForTabDrop() {
         mActiveStrategy = mTabStrategy;
     }
 
+    private static class DragDropReorderStrategy implements ReorderStrategy {
+
+        @Override
+        public void startReorderMode(
+                StripLayoutTab[] stripTabs,
+                @NonNull StripLayoutView interactingView,
+                float effectiveTabWidth,
+                float x) {
+            // TODO(crbug.com/381285152): Implement.
+        }
+
+        @Override
+        public void updateReorderPosition(
+                StripLayoutView[] stripViews,
+                StripLayoutGroupTitle[] groupTitles,
+                StripLayoutTab[] stripTabs,
+                float deltaX) {
+            // TODO(crbug.com/381285152): Implement.
+        }
+
+        @Override
+        public void stopReorderMode(
+                StripLayoutGroupTitle[] groupTitles, StripLayoutTab[] stripTabs) {
+            // TODO(crbug.com/381285152): Implement.
+        }
+    }
+
     // ============================================================================================
     // Animation helpers
     // ============================================================================================

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

@@ -4,7 +4,23 @@
 
 package org.chromium.chrome.browser.compositor.overlays.strip;
 
+import androidx.annotation.NonNull;
+
 interface ReorderStrategy {
+    /**
+     * Begin reordering the interacting view.
+     *
+     * @param stripTabs The list of {@link StripLayoutTab}.
+     * @param interactingView The interacting {@link StripLayoutView}.
+     * @param effectiveTabWidth The width of a tab, accounting for overlap.
+     * @param x The x coordinate that the reorder action began at.
+     */
+    void startReorderMode(
+            StripLayoutTab[] stripTabs,
+            @NonNull StripLayoutView interactingView,
+            float effectiveTabWidth,
+            float x);
+
     /**
      * Updates the location of the reordering tab. This 1. visually offsets the tab (clamped to the
      * bounds of the strip) and 2. triggers a reorder (with animations) if the threshold is reached.

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

@@ -3817,7 +3817,7 @@ private void startReorderMode(float x, StripLayoutView interactingView) {
             return;
         }
 
-        mReorderDelegate.startReorder(mStripTabs, interactingView, getEffectiveTabWidth(), x);
+        mReorderDelegate.startReorderMode(mStripTabs, interactingView, getEffectiveTabWidth(), x);
     }
 
     void updateStripForExternalTabDrop(float startX) {