cc: Remove impl_transform_is_unknown argument from OcclusionTracker.

cc/trees/occlusion_tracker.h

Index: cc/trees/occlusion_tracker.h
diff --git a/cc/trees/occlusion_tracker.h b/cc/trees/occlusion_tracker.h
index 39cd026a8bccaee934e8906ba9a10a880c6b93d1..a47ce0488b1776889e0a51590a4f0108979491b8 100644
--- a/cc/trees/occlusion_tracker.h
+++ b/cc/trees/occlusion_tracker.h
@@ -49,18 +49,15 @@ class CC_EXPORT OcclusionTracker {
   // |draw_transform| and |impl_draw_transform_is_unknown| are relative to that.
   bool Occluded(const LayerType* render_target,
                 const gfx::Rect& content_rect,
-                const gfx::Transform& draw_transform,
-                bool impl_draw_transform_is_unknown) const;
+                const gfx::Transform& draw_transform) const;
 
   // Gives an unoccluded sub-rect of |content_rect| in the content space of a
   // layer. Used when considering occlusion for a layer that paints/draws
   // something. |render_target| is the contributing layer's render target, and
   // |draw_transform| and |impl_draw_transform_is_unknown| are relative to that.
-  gfx::Rect UnoccludedContentRect(
-      const LayerType* render_target,
-      const gfx::Rect& content_rect,
-      const gfx::Transform& draw_transform,
-      bool impl_draw_transform_is_unknown) const;
+  gfx::Rect UnoccludedContentRect(const LayerType* render_target,
+                                  const gfx::Rect& content_rect,
+                                  const gfx::Transform& draw_transform) const;
 
   // Gives an unoccluded sub-rect of |content_rect| in the content space of the
   // render_target owned by the layer. Used when considering occlusion for a