Use defualt shadow elevation.

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index 0e993ba5ef8bffbe2de8e8dffd029a69e217f66a..3ae5cbf7e5c755550cf7455509a8ecca8f5471cc 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -1593,7 +1593,7 @@ void ShellSurface::UpdateShadow() {
     if (shadow_underlay_)
       shadow_underlay_->Hide();
   } else {
-    wm::SetShadowElevation(window, wm::ShadowElevation::MEDIUM);
+    wm::SetShadowElevation(window, wm::ShadowElevation::DEFAULT);
     gfx::Rect shadow_content_bounds =
         gfx::ScaleToEnclosedRect(shadow_content_bounds_, 1.f / scale_);
 
@@ -1727,9 +1727,6 @@ void ShellSurface::UpdateShadow() {
     // small style shadow for them.
     if (!activatable_)
       shadow->SetElevation(wm::ShadowElevation::SMALL);
-    // We don't have rounded corners unless frame is enabled.
-    if (!frame_enabled_)
-      shadow->SetRoundedCornerRadius(0);

[oshima, 2017/05/08 11:22:02]

This is causing b/37254594

   }
 }