printing::Metafile:  Simplify OS_MACOSX-specific code path

  - printing::Metafile
      * move MacRenderPageParams to PdfMetafileCg
      * remove virtual RenderPage()
  - printing::PdfMetafileCg
      * Add MacRenderPageParams
      * RenderPage no longer an override
  - printing::PdfMetafileSkia
      * no longer implment RenderPage()
      * code moved to printing::PrintedDocument::RenderPrintedPage()

This will help isolate BUG=chromium:374359

R=thestig@chromium.org

Review-Url: https://codereview.chromium.org/2802093006
Cr-Commit-Position: refs/heads/master@{#463828}
7 files changed