Add a top shadow to material design omnibox dropdown

chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc

Index: chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
diff --git a/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc b/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
index b2c8d9443454123b70d159e98a47b36c31dc16ae..dfc47bde45cb7c4c1dafce65a752c23eb3187151 100644
--- a/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
+++ b/chrome/browser/ui/views/omnibox/omnibox_popup_contents_view.cc
@@ -69,6 +69,7 @@ OmniboxPopupContentsView::OmniboxPopupContentsView(
   set_owned_by_client();
 
   ui::ThemeProvider* theme = location_bar_view_->GetThemeProvider();
+  top_shadow_ = theme->GetImageSkiaNamed(IDR_OMNIBOX_DROPDOWN_SHADOW_TOP);
   int bottom_shadow_asset = ui::MaterialDesignController::IsModeMaterial() ?
       IDR_OMNIBOX_DROPDOWN_SHADOW_BOTTOM : IDR_BUBBLE_B;
   bottom_shadow_ = theme->GetImageSkiaNamed(bottom_shadow_asset);
@@ -194,10 +195,18 @@ void OmniboxPopupContentsView::UpdatePopupAppearance() {
   for (size_t i = result_size; i < AutocompleteResult::kMaxMatches; ++i)
     child_at(i)->SetVisible(false);
 
+  // The additional overlap is needed for material design so that the content
+  // separator beneath the toolbar is not visible underneath the transparent
+  // shadow asset.

[Peter Kasting, 2015/08/29 01:00:23]

OK, so if we move the comment in the other file out, I would replace the comment
here with something like the following, that gives the info that used to be in
that other comment and expands on it a bit:

"In non-material mode, we want the popup to appear is if it's overlaying the top
of the page content, i.e. is flush against the client edge at the bottom of the
toolbar.  However, if the bookmark bar is attached, we want to draw over it (so
as not to push the results below it), but that means the toolbar won't be
drawing a client edge separating itself from the popup.  So we unconditionally
overlap the toolbar by the thickness of the client edge and draw our own edge
(see OnPaint()), which fixes the attached bookmark bar case without breaking the
other case."

[tdanderson, 2015/08/31 15:23:19]

Done.

+  int top_edge_overlap = views::NonClientFrameView::kClientEdgeThickness;
+  if (ui::MaterialDesignController::IsModeMaterial())

[Peter Kasting, 2015/08/29 01:00:23]

...Then above this line, I'd add a further comment:

"In material mode, we cover the bookmark bar similarly, but instead of appearing
below the client edge, we want the popup to appear to overlay the bottom of the
toolbar.  So instead of drawing a client edge atop the popup, we shift the popup
to completely cover the client edge, and then draw an additional semitransparent
shadow above that.  So the total overlap necessary is the client edge thickness
plus the shadow height."

[tdanderson, 2015/08/31 15:23:19]

Done.

+    top_edge_overlap += top_shadow_->height();
+
   gfx::Point top_left_screen_coord;
   int width;
   location_bar_view_->GetOmniboxPopupPositioningInfo(
-      &top_left_screen_coord, &width, &start_margin_, &end_margin_);
+      &top_left_screen_coord, &width, &start_margin_,
+      &end_margin_, top_edge_overlap);
   gfx::Rect new_target_bounds(top_left_screen_coord,
                               gfx::Size(width, CalculatePopupHeight()));
 
@@ -431,10 +440,15 @@ const char* OmniboxPopupContentsView::GetClassName() const {
 
 void OmniboxPopupContentsView::OnPaint(gfx::Canvas* canvas) {
   // Top border.
-  canvas->FillRect(
-      gfx::Rect(0, 0, width(), views::NonClientFrameView::kClientEdgeThickness),
-      ThemeProperties::GetDefaultColor(
-          ThemeProperties::COLOR_TOOLBAR_SEPARATOR));
+  if (ui::MaterialDesignController::IsModeMaterial()) {
+    canvas->TileImageInt(*top_shadow_, 0, 0, width(), top_shadow_->height());
+  } else {
+    canvas->FillRect(
+        gfx::Rect(0, 0, width(),
+                  views::NonClientFrameView::kClientEdgeThickness),
+        ThemeProperties::GetDefaultColor(
+            ThemeProperties::COLOR_TOOLBAR_SEPARATOR));
+  }
 
   // Bottom border.
   canvas->TileImageInt(*bottom_shadow_, 0, height() - bottom_shadow_->height(),