cc: Free gpu resources when we are invisible or TM is oom.

cc/resources/software_rasterizer.h

Index: cc/resources/software_rasterizer.h
diff --git a/cc/resources/software_rasterizer.h b/cc/resources/software_rasterizer.h
index 6cb751f38b9e6b66dcff495465f8debe595b3a65..1835de9a0991d0805579d334af55f6feacc37ee0 100644
--- a/cc/resources/software_rasterizer.h
+++ b/cc/resources/software_rasterizer.h
@@ -26,6 +26,8 @@ class CC_EXPORT SoftwareRasterizer : public Rasterizer {
       ResourcePool* resource_pool,
       ResourceFormat resource_format,
       const UpdateTileDrawInfoCallback& update_tile_draw_info) override;
+  void ClearCache() override {}
+  void RestoreCacheLimits() override {}
 
  private:
   SoftwareRasterizer();