Restore classic zero state search box text colors.

This CL addresses changes in:

https://chromium-review.googlesource.com/c/chromium/src/+/2425623

Bug: 1134800
Change-Id: I95d8508a817e2b2d32885db84c5ce5129eee52d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2464443
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816397}

ash/search_box/search_box_view_base.cc

@@ -47,6 +47,10 @@ constexpr SkColor kSelectedColor = SkColorSetARGB(15, 0, 0, 0);
 
 constexpr SkColor kSearchTextColor = SkColorSetRGB(0x33, 0x33, 0x33);
 
+// Color of placeholder text in zero query state.
+constexpr SkColor kZeroQuerySearchboxColor =
+    SkColorSetARGB(0x8A, 0x00, 0x00, 0x00);
+
 }  // namespace
 
 // A background that paints a solid white rounded rect with a thin grey
@@ -337,10 +341,13 @@ void SearchBoxViewBase::SetSearchBoxActive(bool active,
 
   is_search_box_active_ = active;
   UpdateSearchIcon();
+  UpdateBackgroundColor(kSearchBoxBackgroundDefault);
   search_box_->set_placeholder_text_draw_flags(
       active ? (base::i18n::IsRTL() ? gfx::Canvas::TEXT_ALIGN_RIGHT
                                     : gfx::Canvas::TEXT_ALIGN_LEFT)
              : gfx::Canvas::TEXT_ALIGN_CENTER);
+  search_box_->set_placeholder_text_color(active ? kZeroQuerySearchboxColor
+                                                 : search_box_color_);
   search_box_->SetCursorEnabled(active);
 
   if (active) {