Add create note palette action.

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 567c38c137d49ad8ade6c8b3adb76c0d1b5b447b..4a38054e80f1c9794668d2589d0fb0b24e88121c 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -155,6 +155,11 @@ void WmShell::SetShelfDelegateForTesting(
   shelf_delegate_ = std::move(test_delegate);
 }
 
+void WmShell::SetPaletteDelegateForTesting(
+    std::unique_ptr<PaletteDelegate> palette_delegate) {
+  palette_delegate_ = std::move(palette_delegate);
+}
+
 WmShell::WmShell(std::unique_ptr<ShellDelegate> shell_delegate)
     : delegate_(std::move(shell_delegate)),
       focus_cycler_(new FocusCycler),