[Sharesheet] Hide separator before expand.

To more closely align with mocks hide separator before expand.
This prevents the two separators from overlapping when the expand
occurs.

Bug: 1148692
Change-Id: I3b0254b2da65d14907d0260c2e600f1bc8cf39c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574569Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Melissa Zhang <melzhang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834417}

chrome/browser/ui/views/sharesheet/sharesheet_bubble_view.cc

@@ -481,18 +481,20 @@ void SharesheetBubbleView::ExpandButtonPressed() {
   show_expanded_view_ = !show_expanded_view_;
   ResizeBubble(kDefaultBubbleWidth, show_expanded_view_ ? kExpandedBubbleHeight
                                                         : kDefaultBubbleHeight);
-  if (show_expanded_view_) {
-    expand_button_->SetToExpandedState();
-    AnimateToExpandedState();
-  } else {
-    expand_button_->SetToDefaultState();
-  }
+
   // Scrollview has separators that overlaps with |expand_button_separator_|
   // to create a double line when both are visible, so when scrollview is
   // expanded we hide our separator.
   expand_button_separator_->SetVisible(!show_expanded_view_);
   expanded_view_->SetVisible(show_expanded_view_);
   expanded_view_separator_->SetVisible(show_expanded_view_);
+
+  if (show_expanded_view_) {
+    expand_button_->SetToExpandedState();
+    AnimateToExpandedState();
+  } else {
+    expand_button_->SetToDefaultState();
+  }
 }
 
 void SharesheetBubbleView::AnimateToExpandedState() {