fix(material/sidenav): restore focus with correct origin when closing via the backdrop (#23492)

Currently when a sidenav is closed, we restore the focus origin as when it was focused because we don't know what kind of event closed it, however if it happens through the backdrop, we can be fairly certain that it was via mouse.

These changes pass in the `mouse` origin when closing through the backdrop.

Fixes #23484.

Author: crisbeto

src/material/sidenav/drawer.ts

@@ -296,7 +296,7 @@ export class MatDrawer implements AfterContentInit, AfterContentChecked, OnDestr
 
         this._takeFocus();
       } else if (this._isFocusWithinDrawer()) {
-        this._restoreFocus();
+        this._restoreFocus(this._openedVia || 'program');
       }
     });
 
@@ -400,20 +400,18 @@ export class MatDrawer implements AfterContentInit, AfterContentChecked, OnDestr
    * Restores focus to the element that was originally focused when the drawer opened.
    * If no element was focused at that time, the focus will be restored to the drawer.
    */
-  private _restoreFocus() {
+  private _restoreFocus(focusOrigin: Exclude<FocusOrigin, null>) {
     if (this.autoFocus === 'dialog') {
       return;
     }
 
-    // Note that we don't check via `instanceof HTMLElement` so that we can cover SVGs as well.
     if (this._elementFocusedBeforeDrawerWasOpened) {
-      this._focusMonitor.focusVia(this._elementFocusedBeforeDrawerWasOpened, this._openedVia);
+      this._focusMonitor.focusVia(this._elementFocusedBeforeDrawerWasOpened, focusOrigin);
     } else {
       this._elementRef.nativeElement.blur();
     }
 
     this._elementFocusedBeforeDrawerWasOpened = null;
-    this._openedVia = null;
   }
 
   /** Whether focus is currently within the drawer. */
@@ -467,8 +465,8 @@ export class MatDrawer implements AfterContentInit, AfterContentChecked, OnDestr
   _closeViaBackdropClick(): Promise<MatDrawerToggleResult> {
     // If the drawer is closed upon a backdrop click, we always want to restore focus. We
     // don't need to check whether focus is currently in the drawer, as clicking on the
-    // backdrop causes blurring of the active element.
-    return this._setOpen(/* isOpen */ false, /* restoreFocus */ true);
+    // backdrop causes blurs the active element.
+    return this._setOpen(/* isOpen */ false, /* restoreFocus */ true, 'mouse');
   }
 
   /**
@@ -481,28 +479,36 @@ export class MatDrawer implements AfterContentInit, AfterContentChecked, OnDestr
       : Promise<MatDrawerToggleResult> {
     // If the focus is currently inside the drawer content and we are closing the drawer,
     // restore the focus to the initially focused element (when the drawer opened).
-    return this._setOpen(
-        isOpen, /* restoreFocus */ !isOpen && this._isFocusWithinDrawer(), openedVia);
+    if (isOpen && openedVia) {
+      this._openedVia = openedVia;
+    }
+
+    const result = this._setOpen(isOpen, /* restoreFocus */ !isOpen && this._isFocusWithinDrawer(),
+      this._openedVia || 'program');
+
+    if (!isOpen) {
+      this._openedVia = null;
+    }
+
+    return result;
   }
 
   /**
    * Toggles the opened state of the drawer.
    * @param isOpen Whether the drawer should open or close.
    * @param restoreFocus Whether focus should be restored on close.
-   * @param openedVia Focus origin that can be optionally set when opening a drawer. The
-   *   origin will be used later when focus is restored on drawer close.
+   * @param focusOrigin Origin to use when restoring focus.
    */
-  private _setOpen(isOpen: boolean, restoreFocus: boolean, openedVia: FocusOrigin = 'program')
-      : Promise<MatDrawerToggleResult> {
+  private _setOpen(isOpen: boolean, restoreFocus: boolean, focusOrigin: Exclude<FocusOrigin, null>):
+    Promise<MatDrawerToggleResult> {
     this._opened = isOpen;
 
     if (isOpen) {
       this._animationState = this._enableAnimations ? 'open' : 'open-instant';
-      this._openedVia = openedVia;
     } else {
       this._animationState = 'void';
       if (restoreFocus) {
-        this._restoreFocus();
+        this._restoreFocus(focusOrigin);
       }
     }