Migrate from MathUtil::inverse() to gfx::Transform::GetInverse()

cc/gl_renderer.cc

Index: cc/gl_renderer.cc
diff --git a/cc/gl_renderer.cc b/cc/gl_renderer.cc
index bb4ec4d3ee99d55d33be2886d435eee999f986cd..a8e8e6bf448e795db8e99f701d95a52a44c52be6 100644
--- a/cc/gl_renderer.cc
+++ b/cc/gl_renderer.cc
@@ -526,10 +526,10 @@ void GLRenderer::drawRenderPassQuad(DrawingFrame& frame, const RenderPassDrawQua
     gfx::Transform contentsDeviceTransform = MathUtil::to2dTransform(frame.windowMatrix * frame.projectionMatrix * quadRectMatrix);
 
     // Can only draw surface if device matrix is invertible.
-    if (!contentsDeviceTransform.IsInvertible())
+    gfx::Transform contentsDeviceTransformInverse(gfx::Transform::kSkipInitialization);
+    if (!contentsDeviceTransform.GetInverse(&contentsDeviceTransformInverse))
         return;
 
-    gfx::Transform contentsDeviceTransformInverse = MathUtil::inverse(contentsDeviceTransform);
     scoped_ptr<ScopedResource> backgroundTexture = drawBackgroundFilters(
         frame, quad, renderPass->background_filters,
         contentsDeviceTransform, contentsDeviceTransformInverse);
@@ -867,8 +867,9 @@ void GLRenderer::drawTileQuad(const DrawingFrame& frame, const TileDrawQuad* qua
         LayerQuad deviceQuad(leftEdge, topEdge, rightEdge, bottomEdge);
 
         // Map device space quad to local space. deviceTransform has no 3d component since it was generated with to2dTransform() so we don't need to project.
-        gfx::Transform deviceTransformInverse = MathUtil::inverse(deviceTransform);
-        localQuad = MathUtil::mapQuad(deviceTransformInverse, deviceQuad.ToQuadF(), clipped);
+        gfx::Transform inverseDeviceTransform(gfx::Transform::kSkipInitialization);
+        deviceTransform.GetInverse(&inverseDeviceTransform);

[danakj, 2012/12/19 05:23:06]

We checked deviceTransform.IsInvertible way up near the top of this method.

Instead, can we do the GetInverse() up there, so we don't have to do the work of
IsInvertible+Invert?

+        localQuad = MathUtil::mapQuad(inverseDeviceTransform, deviceQuad.ToQuadF(), clipped);
 
         // We should not DCHECK(!clipped) here, because anti-aliasing inflation may cause deviceQuad to become
         // clipped. To our knowledge this scenario does not need to be handled differently than the unclipped case.