app/clipboard: delete

The implementation was too optimistic: some platforms require a
window context for accessing the clipboard.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/clipboard/clipboard.go

@@ -1,20 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-// +build android
-
-// Package clipboard accesses the system clipboard.
-package clipboard
-
-import (
-	"gioui.org/app/internal/window"
-)
-
-// Read the content of the clipboard as a string.
-func Read() (string, error) {
-	return window.ReadClipboard()
-}
-
-// Write a string to the clipboard.
-func Write(s string) error {
-	return window.WriteClipboard(s)
-}

app/clipboard/clipboard_test.go

@@ -1,21 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-// +build android
-
-package clipboard
-
-import "testing"
-
-func TestClipboard(t *testing.T) {
-	const want = "Hello, 世界"
-	if err := Write(want); err != nil {
-		t.Fatal(err)
-	}
-	got, err := Read()
-	if err != nil {
-		t.Fatal(err)
-	}
-	if got != want {
-		t.Errorf("read %q from the clipboard, wanted %q", got, want)
-	}
-}