fix(material/autocomplete): autocomplete panel top cut off in mobile landscape mode

Fixes a bug in the Angular Material Autocomplete component where the
autocomplete panel top was being cut off by the screen in mobile
landscape mode. Updates previous fix to target adjustments on
HandsetLandscape only.

Fixes b/284148377

Author: essjay05

src/material/autocomplete/autocomplete-trigger.ts

@@ -31,6 +31,7 @@ import {
 import {DOCUMENT} from '@angular/common';
 import {Directionality} from '@angular/cdk/bidi';
 import {DOWN_ARROW, ENTER, ESCAPE, TAB, UP_ARROW, hasModifierKey} from '@angular/cdk/keycodes';
+import {BreakpointObserver, Breakpoints} from '@angular/cdk/layout';
 import {_getEventTarget} from '@angular/cdk/platform';
 import {TemplatePortal} from '@angular/cdk/portal';
 import {ViewportRuler} from '@angular/cdk/scrolling';
@@ -239,6 +240,8 @@ export class MatAutocompleteTrigger
     private _viewContainerRef: ViewContainerRef,
     private _zone: NgZone,
     private _changeDetectorRef: ChangeDetectorRef,
+    /** Subscription to viewport orientation changes. */
+    private _breakpointObserver: BreakpointObserver,
     @Inject(MAT_AUTOCOMPLETE_SCROLL_STRATEGY) scrollStrategy: any,
     @Optional() private _dir: Directionality | null,
     @Optional() @Inject(MAT_FORM_FIELD) @Host() private _formField: MatFormField | null,
@@ -880,14 +883,25 @@ export class MatAutocompleteTrigger
   }
 
   private _getOverlayPosition(): PositionStrategy {
+    // Set default Overlay Position
     const strategy = this._overlay
       .position()
       .flexibleConnectedTo(this._getConnectedElement())
-      .withFlexibleDimensions(true)
-      .withGrowAfterOpen(true)
-      .withViewportMargin(8)
+      .withFlexibleDimensions(false)
       .withPush(false);
 
+    // Check breakpoint if being viewed in HandsetLandscape
+    const isHandsetLandscape = this._breakpointObserver
+      .observe(Breakpoints.HandsetLandscape)
+      .subscribe(result => {
+        return result.matches;
+      });
+    // Apply HandsetLandscape settings to prevent overlay cutoff in that breakpoint
+    // Fixes b/284148377
+    if (isHandsetLandscape) {
+      strategy.withFlexibleDimensions(true).withGrowAfterOpen(true).withViewportMargin(8);
+    }
+
     this._setStrategyPositions(strategy);
     this._positionStrategy = strategy;
     return strategy;