Add non-member non-mutating methods for common gfx::Rect operations.

This adds non-member methods that return a new Rect (or RectF) object
as their result instead of mutating an existing rect. We add:

Rect gfx::IntersectRects(Rect, Rect)
RectF gfx::IntersectRects(RectF, RectF)
Rect gfx::UnionRects(Rect, Rect)
RectF gfx::UnionRects(RectF, RectF)
Rect gfx::SubtractRects(Rect, Rect)
RectF gfx::SubtractRects(RectF, RectF)
RectF gfx::ScaleRect(RectF, scale)
RectF gfx::ScaleRect(RectF, x_scale, y_scale)

In CL https://codereview.chromium.org/11110004/ we made all
member methods of Rect (and RectF) mutate the existing
object, so these methods are added for cases where we want
the result to create a new object instead.

BUG=147395
R=sky

Review URL: https://codereview.chromium.org/11270042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@164760 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 1 insertions, 2 deletions

diff --git a/cc/direct_renderer.cc b/cc/direct_renderer.cc
index ac3ea3c3..d534c1a 100644
--- a/cc/direct_renderer.cc
+++ b/cc/direct_renderer.cc
@@ -186,8 +186,7 @@ void DirectRenderer::drawRenderPass(DrawingFrame& frame, const RenderPass* rende
 
     const QuadList& quadList = renderPass->quadList();
     for (QuadList::constBackToFrontIterator it = quadList.backToFrontBegin(); it != quadList.backToFrontEnd(); ++it) {
-        gfx::RectF quadScissorRect = frame.scissorRectInRenderPassSpace;
-        quadScissorRect.Intersect((*it)->clippedRectInTarget());
+        gfx::RectF quadScissorRect = gfx::IntersectRects(frame.scissorRectInRenderPassSpace, (*it)->clippedRectInTarget());
         if (!quadScissorRect.IsEmpty()) {
             enableScissorTestRect(moveScissorToWindowSpace(frame, quadScissorRect));
             drawQuad(frame, *it);