sync compositor: pass simple gfx types by const ref

See bug for reasoning

BUG=159273

Review URL: https://codereview.chromium.org/1417893006

Cr-Commit-Position: refs/heads/master@{#356653}
void BrowserViewRenderer::SetDipScale(float dip_scale) {
  dip_scale_ = dip_scale;
  CHECK_GT(dip_scale_, 0.f);
}

void BrowserViewRenderer::SetDipScale(float dip_scale) {
  dip_scale_ = dip_scale;
  CHECK_GT(dip_scale_, 0.f);
}
