Remove unnecessary SchedulePaint on BrowserNonClientFrameViewAsh

This SchedulePaint causes to request repaints of the entire
browser frame when overview-mode / splitview-mode changes. This
can cause significant load on GPU, especially when there are
many browser windows, and actually this is unnecessary because
View::SetVisible change invalidates the painting of its bounds.

I tried on nocturne with 15 browser windows; the toggle overview
by key changes the Overview.AnimationSmoothness histogram as;
- Enter: 18.9 -> 86.9
- Exit: 7.2 -> 61.3

Bug: 949227
Test: manually
Change-Id: I9a71776a66d4b609027d18c17f6796114fdb3f82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1560019Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649246}

chrome/browser/ui/views/frame/browser_non_client_frame_view_ash.cc

@@ -757,9 +757,6 @@ bool BrowserNonClientFrameViewAsh::ShouldPaint() const {
 
 void BrowserNonClientFrameViewAsh::OnOverviewOrSplitviewModeChanged() {
   caption_button_container_->SetVisible(ShouldShowCaptionButtons());
-
-  // Schedule a paint to show or hide the header.
-  SchedulePaint();
 }
 
 std::unique_ptr<ash::FrameHeader>