Prevent maximize/minimize/fullscreen-ize window in trusted pinned mode.

ash/common/wm/default_state.cc

Index: ash/common/wm/default_state.cc
diff --git a/ash/common/wm/default_state.cc b/ash/common/wm/default_state.cc
index d17253e6a9187f68018c7fd5e483d8015509fa50..146c61fa148d88d3b8de49e04b0bccac9cf283ad 100644
--- a/ash/common/wm/default_state.cc
+++ b/ash/common/wm/default_state.cc
@@ -167,6 +167,10 @@ void DefaultState::OnWMEvent(WindowState* window_state, const WMEvent* event) {
   if (ProcessWorkspaceEvents(window_state, event))
     return;
 
+  // Do not change the PINNED window state if this is not unpin event.
+  if (window_state->IsTrustedPinned() && event->type() != WM_EVENT_NORMAL)
+    return;
+
   if (ProcessCompoundEvents(window_state, event))
     return;