assistant: Not show suggestions for launcher query

If embedded Assistant Ui is opened from kLauncherSearchResult, do not
show the conversation starter suggestion chips.

Bug: b/132442518
Test: manual
Change-Id: I871485afaca0d140dc87b029ddab6b99a9312a05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610500Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660067}

ash/assistant/ui/main_stage/suggestion_container_view.cc

@@ -192,8 +192,10 @@ void SuggestionContainerView::OnUiVisibilityChanged(
     AssistantVisibility old_visibility,
     base::Optional<AssistantEntryPoint> entry_point,
     base::Optional<AssistantExitPoint> exit_point) {
-  if (assistant::util::IsStartingSession(new_visibility, old_visibility)) {
-    // Show conversation starters at the start of a new Assistant session.
+  if (assistant::util::IsStartingSession(new_visibility, old_visibility) &&
+      entry_point.value() != AssistantEntryPoint::kLauncherSearchResult) {
+    // Show conversation starters at the start of a new Assistant session except
+    // when the user already started a query in Launcher quick search box (QSB).
     OnConversationStartersChanged(
         delegate_->GetCacheModel()->GetConversationStarters());
     return;