Add a test api for checking if system supports TaskSnapshot

Use this test api to make sure testing
KeyboardVisibilityControlTest#testRestoreImeVisibility_.* that
requires the system supporting TaskSnapshot mechanism, otherwise skip
the test when the system doesn't support it.

Bug: 184978234
Test: m checkapi & atest KeyboardVisibilityControlTest
Change-Id: I777053aeeb6a2734a4bbd37711cf56ced41c1bd9

core/api/test-current.txt

@@ -2730,6 +2730,7 @@ package android.view {
   public interface WindowManager extends android.view.ViewManager {
     method public default int getDisplayImePolicy(int);
     method public default void holdLock(android.os.IBinder, int);
+    method public default boolean isTaskSnapshotSupported();
     method public default void setDisplayImePolicy(int, int);
     method public default void setForceCrossWindowBlurDisabled(boolean);
     method public default void setShouldShowSystemDecors(int, boolean);

core/java/android/view/IWindowManager.aidl

@@ -827,4 +827,6 @@ interface IWindowManager
     void unregisterCrossWindowBlurEnabledListener(ICrossWindowBlurEnabledListener listener);
 
     void setForceCrossWindowBlurDisabled(boolean disable);
+
+    boolean isTaskSnapshotSupported();
 }

core/java/android/view/WindowManager.java

@@ -4544,4 +4544,13 @@ public interface WindowManager extends ViewManager {
     default void holdLock(IBinder token, int durationMs) {
         throw new UnsupportedOperationException();
     }
+
+    /**
+     * Used for testing to check if the system supports TaskSnapshot mechanism.
+     * @hide
+     */
+    @TestApi
+    default boolean isTaskSnapshotSupported() {
+        return false;
+    }
 }

core/java/android/view/WindowManagerImpl.java

@@ -335,4 +335,13 @@ public final class WindowManagerImpl implements WindowManager {
         } catch (RemoteException e) {
         }
     }
+
+    @Override
+    public boolean isTaskSnapshotSupported() {
+        try {
+            return WindowManagerGlobal.getWindowManagerService().isTaskSnapshotSupported();
+        } catch (RemoteException e) {
+        }
+        return false;
+    }
 }

services/core/java/com/android/server/wm/TaskSnapshotController.java

@@ -486,7 +486,7 @@ class TaskSnapshotController {
         return builder.build();
     }
 
-    private boolean shouldDisableSnapshots() {
+    boolean shouldDisableSnapshots() {
         return mIsRunningOnWear || mIsRunningOnTv || mIsRunningOnIoT;
     }
 

services/core/java/com/android/server/wm/WindowManagerService.java

@@ -8712,6 +8712,13 @@ public class WindowManagerService extends IWindowManager.Stub
         mDisplayHashController.setDisplayHashThrottlingEnabled(enable);
     }
 
+    @Override
+    public boolean isTaskSnapshotSupported() {
+        synchronized (mGlobalLock) {
+            return !mTaskSnapshotController.shouldDisableSnapshots();
+        }
+    }
+
     void generateDisplayHash(Session session, IWindow window, Rect boundsInWindow,
             String hashAlgorithm, RemoteCallback callback) {
         final SurfaceControl displaySurfaceControl;