Revert of Specifies transparent background for the label in TileItemView....

Revert of Specifies transparent background for the label in TileItemView. (patchset #2 id:10002 of https://codereview.chromium.org/655823005/)

Reason for revert:
Introduces static initializer, see https://build.chromium.org/p/chromium/builders/Linux%20x64/builds/72389

Original issue's description:
> Specifies transparent background for the label in TileItemView.
>
> We may not use single background when it's in Athena (it's not
> used yet though).
>
> BUG=425717
> R=xiyuan@chromium.org
> TEST=manually
>
> Committed: https://crrev.com/3b74c2c950e3681a94601f61d48a6ff0e25f06f8
> Cr-Commit-Position: refs/heads/master@{#301007}

TBR=xiyuan@chromium.org,mukai@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=425717

Review URL: https://codereview.chromium.org/674083002

Cr-Commit-Position: refs/heads/master@{#301066}

ui/app_list/views/tile_item_view.cc

@@ -11,7 +11,6 @@
 #include "ui/app_list/app_list_view_delegate.h"
 #include "ui/app_list/search_result.h"
 #include "ui/app_list/views/app_list_main_view.h"
-#include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_analysis.h"
 #include "ui/gfx/color_utils.h"
@@ -25,14 +24,6 @@ namespace {
 const int kTileSize = 90;
 const int kTileHorizontalPadding = 10;
 
-// In Windows, transparent background color will cause ugly text rendering,
-// therefore kContentsBackgroundColor should be used. See crbug.com/406989
-#if defined(OS_CHROMEOS)
-const SkColor kTitleBackgroundColor = SK_ColorTRANSPARENT;
-#else
-const SkColor kTitleBackgroundColor = app_list::kContentsBackgroundColor;
-#endif
-
 }  // namespace
 
 namespace app_list {
@@ -54,7 +45,7 @@ TileItemView::TileItemView()
   title_->SetAutoColorReadabilityEnabled(false);
   title_->SetEnabledColor(kGridTitleColor);
   title_->set_background(views::Background::CreateSolidBackground(
-      kTitleBackgroundColor));
+      app_list::kContentsBackgroundColor));
   title_->SetFontList(rb.GetFontList(kItemTextFontStyle));
   title_->SetHorizontalAlignment(gfx::ALIGN_CENTER);