Snap root surface to physical pixel

The root surface needs to be snapped if the shell surface uses chrome side caption.

This CL also removes "!allow_set_bounds_direct" check when
snapping the window in WindowState. This should have been removed
when we switched to relative surface hierarchy.

Bug: 836076
Test: manually tested with fractional scale factor.

Change-Id: Iadc06572279dec42f8d792424cee76481a94fd55
Reviewed-on: https://chromium-review.googlesource.com/1025371
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: David Reveman <reveman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553124}

ash/wm/window_state.cc

@@ -599,8 +599,7 @@ void WindowState::SetBoundsDirect(const gfx::Rect& bounds) {
         std::max(min_size.height(), actual_new_bounds.height()));
   }
   BoundsSetter().SetBounds(window_, actual_new_bounds);
-  if (!allow_set_bounds_direct())
-    wm::SnapWindowToPixelBoundary(window_);
+  wm::SnapWindowToPixelBoundary(window_);
 }
 
 void WindowState::SetBoundsConstrained(const gfx::Rect& bounds) {

components/exo/shell_surface_base.cc

@@ -36,6 +36,7 @@
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/class_property.h"
 #include "ui/compositor/compositor.h"
+#include "ui/compositor/dip_util.h"
 #include "ui/compositor_extra/shadow.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
@@ -1351,6 +1352,11 @@ void ShellSurfaceBase::UpdateSurfaceBounds() {
       root_surface_origin().OffsetFromOrigin(), 1.f / GetScale()));
 
   host_window()->SetBounds(gfx::Rect(origin, host_window()->bounds().size()));
+  // The host window might have not been added to the widget yet.
+  if (host_window()->parent()) {
+    ui::SnapLayerToPhysicalPixelBoundary(widget_->GetNativeWindow()->layer(),
+                                         host_window()->layer());
+  }
 }
 
 void ShellSurfaceBase::UpdateShadow() {