Improve GL shader YUV adjustment.

cc/quads/yuv_video_draw_quad.h

Index: cc/quads/yuv_video_draw_quad.h
diff --git a/cc/quads/yuv_video_draw_quad.h b/cc/quads/yuv_video_draw_quad.h
index d0581e824032144ffb1075e31e3e44ce2a99a698..fac9351b663c481995cfba3a054957fcabeae530 100644
--- a/cc/quads/yuv_video_draw_quad.h
+++ b/cc/quads/yuv_video_draw_quad.h
@@ -52,7 +52,8 @@ class CC_EXPORT YUVVideoDrawQuad : public DrawQuad {
               unsigned a_plane_resource_id,
               ColorSpace color_space,
               float offset,
-              float multiplier);
+              float multiplier,
+              int bits_per_channel);
 
   void SetAll(const SharedQuadState* shared_quad_state,
               const gfx::Rect& rect,
@@ -72,7 +73,8 @@ class CC_EXPORT YUVVideoDrawQuad : public DrawQuad {
               unsigned a_plane_resource_id,
               ColorSpace color_space,
               float offset,
-              float multiplier);
+              float multiplier,
+              int bits_per_channel);
 
   gfx::RectF ya_tex_coord_rect;
   gfx::RectF uv_tex_coord_rect;
@@ -81,6 +83,7 @@ class CC_EXPORT YUVVideoDrawQuad : public DrawQuad {
   ColorSpace color_space;
   float resource_offset = 0.0f;
   float resource_multiplier = 1.0f;
+  int bits_per_channel = 8;
 
   static const YUVVideoDrawQuad* MaterialCast(const DrawQuad*);