[Android] tab switcher exit animation gray line bug fix.

On existing tab switcher, a gray line was shown between toolbar and
content unintentionally. This is clearly noticiable when the tab is NTP.

Problems:
- The border layer includes inner shadow that's not covered by fading-
  in toolbar.
- The border layer is shifted by (0.5, 0.5) to avoid jaggies.
- Linear interpolation of border layer on rasterization makes the top
  edge bleeding below.

Fixes:
- Seperates border layer and its inner shadow.
- Also shifts the toolbar fading-in layer by (0.5, 0.5)
- Use nearest neighbor rasterization when the toolbar is visible.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
BUG=None

Review URL: https://codereview.chromium.org/1584573005

Cr-Commit-Position: refs/heads/master@{#371149}

1 files changed, 2 insertions, 0 deletions

diff --git a/cc/layers/nine_patch_layer.h b/cc/layers/nine_patch_layer.h
index ff76663..a2c37e1 100644
--- a/cc/layers/nine_patch_layer.h
+++ b/cc/layers/nine_patch_layer.h
@@ -39,6 +39,7 @@ class CC_EXPORT NinePatchLayer : public UIResourceLayer {
   // y-stretched to fit.
   void SetAperture(const gfx::Rect& aperture);
   void SetFillCenter(bool fill_center);
+  void SetNearestNeighbor(bool nearest_neighbor);
 
  private:
   explicit NinePatchLayer(const LayerSettings& settings);
@@ -47,6 +48,7 @@ class CC_EXPORT NinePatchLayer : public UIResourceLayer {
 
   gfx::Rect border_;
   bool fill_center_;
+  bool nearest_neighbor_;
 
   // The transparent center region that shows the parent layer's contents in
   // image space.