Replaced synthetic MouseEvent in CustomButton::AcceleratorPressed() with just an Event.

ui/base/accelerators/accelerator.cc

Index: ui/base/accelerators/accelerator.cc
diff --git a/ui/base/accelerators/accelerator.cc b/ui/base/accelerators/accelerator.cc
index 8b8d14e1a5fbee1cef1c0cbd95b1d9f6ac8cecbb..837c514c22548e24205f745f33e36fae462eec1f 100644
--- a/ui/base/accelerators/accelerator.cc
+++ b/ui/base/accelerators/accelerator.cc
@@ -67,6 +67,13 @@ int Accelerator::MaskOutKeyEventFlags(int flags) {
   return flags & kModifierMask;
 }
 
+KeyEvent Accelerator::ToKeyEvent() const {
+  return KeyEvent(key_state() == Accelerator::KeyState::PRESSED
+                      ? ET_KEY_PRESSED
+                      : ET_KEY_RELEASED,
+                  key_code(), modifiers());
+}
+
 Accelerator& Accelerator::operator=(const Accelerator& accelerator) {
   if (this != &accelerator) {
     key_code_ = accelerator.key_code_;