Code: void BrowserViewRenderer::DidOverscroll(gfx::Vector2dF accumulated_overscroll,
                                        gfx::Vector2dF latest_overscroll_delta,
                                        gfx::Vector2dF current_fling_velocity) {
   const float physical_pixel_scale = dip_scale_ * page_scale_factor_;
   if (accumulated_overscroll == latest_overscroll_delta)
     overscroll_rounding_error_ = gfx::Vector2dF();
  gfx::Vector2dF scaled_overscroll_delta =
      gfx::ScaleVector2d(latest_overscroll_delta, physical_pixel_scale);
  gfx::Vector2d rounded_overscroll_delta = gfx::ToRoundedVector2d(
      scaled_overscroll_delta + overscroll_rounding_error_);
  overscroll_rounding_error_ =
      scaled_overscroll_delta - rounded_overscroll_delta;
  gfx::Vector2dF fling_velocity_pixels =
      gfx::ScaleVector2d(current_fling_velocity, physical_pixel_scale);

  client_->DidOverscroll(rounded_overscroll_delta, fling_velocity_pixels);
}

Vulnerability Type: DoS 
CWE ID: CWE-399
Summary: Use-after-free vulnerability in the StyleElement::removedFromDocument function in core/dom/StyleElement.cpp in Blink, as used in Google Chrome before 35.0.1916.114, allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via crafted JavaScript code that triggers tree mutation.
Commit Message: 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}