Flex layout now reports what view caused a size inversion.

Provides a little more information when a particular pathological case
is reached. This case can happen due to quirks in Views and almost
always indicates a bug in the infrastructure so it's important to know
what view is causing the problem.

Change-Id: I9527773a2a8660fcb5646c6802a489772db8a6e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1876914
Commit-Queue: Dana Fried <dfried@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Auto-Submit: Dana Fried <dfried@chromium.org>
Reviewed-by: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708763}

ui/views/layout/flex_layout.cc

@@ -417,7 +417,8 @@ void FlexLayout::InitializeChildData(
       // We should revisit whether this is a valid assumption for text views
       // in vertical layouts.
       DCHECK_GE(flex_child.preferred_size.main(),
-                flex_child.current_size.main());
+                flex_child.current_size.main())
+          << " in " << child->GetClassName();
 
       // Keep track of non-hidden flex controls.
       const bool can_flex =