Revert "BottomSheet background color."

This reverts commit 28ffd7d7.

Reason for revert: This change breaks the "shadow" on the top border
of the bottom sheet.

Original change's description:
> BottomSheet background color.
>
> This fixes the bottom sheet background color across the board to use
> "default_bg_color_elev_3". Doing this here allows to keep the rounded
> top.
>
> "default_bg_color_elev_3" is chosen as a standin for "default_bg_color"
> which is not yet available. See also here:
> * crbug/1002594
> * crrev/c/1798348
>
> Light mode: https://screenshot.googleplex.com/d1T3vfBAxzn
> Dark mode: https://screenshot.googleplex.com/xQAVqz7qNbg
>
> Bug: 1035985
> Bug: b/146412594
> Change-Id: I7c0652bcfc799cd233ce6c793459427461ad9af6
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974150
> Reviewed-by: Clemens Arbesser <arbesser@google.com>
> Reviewed-by: Matthew Jones <mdjones@chromium.org>
> Commit-Queue: Sandro Maggi <sandromaggi@google.com>
> Cr-Commit-Position: refs/heads/master@{#726780}

TBR=mdjones@google.com,mdjones@chromium.org,arbesser@google.com,sandromaggi@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: b/146412594
Bug: 1036757
Bug: b/147343555
Change-Id: Ief00f61c7088f1e4f1437fd8760c68c39ca1dc76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1991562Reviewed-by: Sandro Maggi <sandromaggi@google.com>
Commit-Queue: Sandro Maggi <sandromaggi@google.com>
Auto-Submit: Sandro Maggi <sandromaggi@google.com>
Cr-Commit-Position: refs/heads/master@{#729380}

chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java

@@ -10,7 +10,6 @@ import android.animation.ValueAnimator;
 import android.content.Context;
 import android.graphics.Color;
 import android.graphics.Rect;
-import android.support.v4.view.ViewCompat;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
@@ -275,9 +274,6 @@ class BottomSheet extends FrameLayout
                 (TouchRestrictingFrameLayout) findViewById(R.id.bottom_sheet_content);
         mBottomSheetContentContainer.setBottomSheet(this);
         mBottomSheetContentContainer.setBackgroundResource(R.drawable.top_round);
-        // TODO(b/146412594): Replace the color with default_bg_color once available.
-        ViewCompat.setBackgroundTintList(mBottomSheetContentContainer,
-                getResources().getColorStateList(R.color.default_bg_color_elev_3));
 
         mContainerWidth = root.getWidth();
         mContainerHeight = root.getHeight();