Remove makeKeyAndOrderFront: from WebContentsViewMac::Focus().

WebContentsView::Focus() is supposed to update the first responder of the
Window, not make the window focused. The latter should go through
WebContentsDelegate::ActivateContents().

This logic is usually a no-op because the window receiving the call is the
active window. But in the case where the user quickly switches windows, this can
cause the old window to re-take focus.

This logic was added in 2009 not because it had the right semantics, but to
match the behavior of Windows: http://codereview.chromium.org/165492.

Bug: 859614
Change-Id: I2bc44a825d93159d774c632da17cc2f2d151fc3a
Reviewed-on: https://chromium-review.googlesource.com/1124772Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573344}

content/browser/web_contents/web_contents_view_mac.mm

@@ -198,9 +198,6 @@ void WebContentsViewMac::Focus() {
   gfx::NativeView native_view = GetNativeViewForFocus();
   NSWindow* window = [native_view window];
   [window makeFirstResponder:native_view];
-  if (![window isVisible])
-    return;
-  [window makeKeyAndOrderFront:nil];
 }
 
 void WebContentsViewMac::SetInitialFocus() {