[StartTablet] Fix transitions between Start surface and NTP homepage …

…on foldable is broken.

The bug exists when the "Start surface refactor" is enabled. In this
CL, we update the check of whether Start surface | Tab switcher is
showing and it works with refactor flag is enabled and disabled.

(cherry picked from commit 38adf0e)

Bug: 1451844
Change-Id: I0b741fc70851e7484840e8d8af603e2e82c09bb1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4595923
Commit-Queue: Xi Han <hanxi@chromium.org>
Reviewed-by: Aishwarya Rajesh <aishwaryarj@google.com>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Cr-Original-Commit-Position: refs/heads/main@{#1154477}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4604830
Cr-Commit-Position: refs/branch-heads/5790@{#539}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

chrome/android/java/src/org/chromium/chrome/browser/ui/fold_transitions/FoldTransitionController.java

@@ -89,11 +89,23 @@ public void saveUiState(
             savedInstanceState.putBoolean(KEYBOARD_VISIBILITY_STATE, true);
         }
 
-        if (mLayoutManagerSupplier.hasValue()
-                && mLayoutManagerSupplier.get().isLayoutVisible(LayoutType.TAB_SWITCHER)) {
-            savedInstanceState.putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
-
-            saveHomeSurfaceState(savedInstanceState, mStartSurfaceSupplier.get(), isIncognito);
+        if (mLayoutManagerSupplier.hasValue()) {
+            // Start surface used a TAB_SWITCHER LayoutType before the START_SURFACE_REFACTOR
+            // feature was supported. Therefore, it is safe to assume that the Tab switcher layout
+            // is actually visible only when the Start surface home page is not showing, and the Tab
+            // switcher visibility state will be saved to the instance state only in this case.
+            // TODO(https://crbug.com/1315676): Clean up the logic once the START_SURFACE_REFACTOR
+            // flag is enabled by default.
+            if (mLayoutManagerSupplier.get().isLayoutVisible(LayoutType.TAB_SWITCHER)
+                    || mLayoutManagerSupplier.get().isLayoutVisible(LayoutType.START_SURFACE)) {
+                if (mStartSurfaceSupplier.hasValue()
+                        && mStartSurfaceSupplier.get().isHomepageShown()) {
+                    saveHomeSurfaceState(
+                            savedInstanceState, mStartSurfaceSupplier.get(), isIncognito);
+                } else {
+                    savedInstanceState.putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
+                }
+            }
         }
     }
 
@@ -130,9 +142,7 @@ static void saveHomeSurfaceState(
             return;
         }
 
-        if (startSurface.isHomepageShown()) {
-            savedInstanceState.putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
-        }
+        savedInstanceState.putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
     }
 
     @VisibleForTesting

chrome/android/junit/src/org/chromium/chrome/browser/ui/fold_transitions/FoldTransitionControllerUnitTest.java

@@ -82,6 +82,8 @@ public class FoldTransitionControllerUnitTest {
     private Bundle mSavedInstanceState;
     @Mock
     private StartSurface mStartSurface;
+    @Mock
+    private OneshotSupplierImpl<StartSurface> mStartSurfaceSupplier;
 
     private FoldTransitionController mFoldTransitionController;
 
@@ -245,25 +247,54 @@ public void testSaveUiState_tabSwitcherNotVisible() {
 
     @Test
     public void testSaveHomeSurfaceState() {
+        doReturn(true).when(mSavedInstanceState).getBoolean(DID_CHANGE_TABLET_MODE);
+
         saveHomeSurfaceState(null, mStartSurface, false);
         saveHomeSurfaceState(mSavedInstanceState, null, false);
-        saveHomeSurfaceState(mSavedInstanceState, mStartSurface, false);
         saveHomeSurfaceState(mSavedInstanceState, mStartSurface, true);
         verify(mSavedInstanceState, never()).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
-        verify(mStartSurface, never()).isHomepageShown();
 
-        // Verifies that saved instance state should not contain RESUME_HOME_SURFACE_ON_MODE_CHANGE
-        // if Start surface isn't shown on phone.
+        // Verifies that saved instance state will have RESUME_HOME_SURFACE_ON_MODE_CHANGE == true
+        // if Start surface is shown on phone.
+        saveHomeSurfaceState(mSavedInstanceState, mStartSurface, false);
+        verify(mSavedInstanceState).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
+    }
+
+    @Test
+    public void testSaveUiStateWithTabSwitcherAndStartSurface() {
         doReturn(true).when(mSavedInstanceState).getBoolean(DID_CHANGE_TABLET_MODE);
+        doReturn(true).when(mLayoutManager).isLayoutVisible(LayoutType.TAB_SWITCHER);
+        // Sets Start surface is disabled.
+        doReturn(false).when(mStartSurfaceSupplier).hasValue();
+        // Tests the case when Tab switcher is showing with Start surface disabled.
+        mFoldTransitionController.saveUiState(mSavedInstanceState, true, false);
+        verify(mSavedInstanceState, never()).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
+        verify(mSavedInstanceState).putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
+
+        // Sets Start surface is enabled.
+        doReturn(true).when(mStartSurfaceSupplier).hasValue();
+        doReturn(mStartSurface).when(mStartSurfaceSupplier).get();
+        // Tests the case when Tab switcher is showing with Start surface enabled.
         doReturn(false).when(mStartSurface).isHomepageShown();
-        saveHomeSurfaceState(mSavedInstanceState, mStartSurface, false);
+        mFoldTransitionController.saveUiState(mSavedInstanceState, true, false);
         verify(mSavedInstanceState, never()).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
+        verify(mSavedInstanceState, times(2)).putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
 
-        // Verifies that saved instance state will have RESUME_HOME_SURFACE_ON_MODE_CHANGE == true
-        // if Start surface is shown on phone.
+        // Tests the case when Start surface is showing with "Start surface refactor" disabled.
         doReturn(true).when(mStartSurface).isHomepageShown();
-        saveHomeSurfaceState(mSavedInstanceState, mStartSurface, false);
+        doReturn(true).when(mLayoutManager).isLayoutVisible(LayoutType.TAB_SWITCHER);
+        mFoldTransitionController.saveUiState(mSavedInstanceState, true, false);
         verify(mSavedInstanceState).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
+        verify(mSavedInstanceState, times(2)).putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
+
+        // Sets the layout when "Start surface refactor" is enabled.
+        doReturn(false).when(mLayoutManager).isLayoutVisible(LayoutType.TAB_SWITCHER);
+        doReturn(true).when(mLayoutManager).isLayoutVisible(LayoutType.START_SURFACE);
+        // Tests the case when Start surface is showing with "Start surface refactor" enabled:
+        doReturn(true).when(mStartSurface).isHomepageShown();
+        mFoldTransitionController.saveUiState(mSavedInstanceState, true, false);
+        verify(mSavedInstanceState, times(2)).putBoolean(RESUME_HOME_SURFACE_ON_MODE_CHANGE, true);
+        verify(mSavedInstanceState, times(2)).putBoolean(TAB_SWITCHER_VISIBILITY_STATE, true);
     }
 
     @Test
@@ -370,6 +401,6 @@ private void initializeController() {
         var layoutManagerSupplier = new ObservableSupplierImpl<LayoutManager>();
         layoutManagerSupplier.set(mLayoutManager);
         mFoldTransitionController = new FoldTransitionController(toolbarManagerSupplier,
-                layoutManagerSupplier, mActivityTabProvider, new OneshotSupplierImpl<>(), mHandler);
+                layoutManagerSupplier, mActivityTabProvider, mStartSurfaceSupplier, mHandler);
     }
 }