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

cc/occlusion_tracker.cc

Index: cc/occlusion_tracker.cc
diff --git a/cc/occlusion_tracker.cc b/cc/occlusion_tracker.cc
index e71c678591e2a8306ea70edd3256114866af3b06..c053fdac06ea2acc2372424c708c0060e3bfec2f 100644
--- a/cc/occlusion_tracker.cc
+++ b/cc/occlusion_tracker.cc
@@ -54,7 +54,7 @@ void OcclusionTrackerBase<LayerType, RenderSurfaceType>::leaveLayer(const LayerI
 template<typename RenderSurfaceType>
 static gfx::Rect screenSpaceClipRectInTargetSurface(const RenderSurfaceType* targetSurface, gfx::Rect screenSpaceClipRect)
 {
-    gfx::Transform inverseScreenSpaceTransform;
+    gfx::Transform inverseScreenSpaceTransform(gfx::Transform::kSkipInitialization);
     if (!targetSurface->screenSpaceTransform().GetInverse(&inverseScreenSpaceTransform))
         return targetSurface->contentRect();
 
@@ -124,7 +124,7 @@ void OcclusionTrackerBase<LayerType, RenderSurfaceType>::enterRenderTarget(const
     bool enteringSubtreeThatMovesPixels = newAncestorThatMovesPixels && newAncestorThatMovesPixels != oldAncestorThatMovesPixels;
 
     bool haveTransformFromScreenToNewTarget = false;
-    gfx::Transform inverseNewTargetScreenSpaceTransform;
+    gfx::Transform inverseNewTargetScreenSpaceTransform(gfx::Transform::kSkipInitialization); // Note carefully, not used if screen space transform is uninvertible.
     if (surfaceTransformsToScreenKnown(newTarget->renderSurface()))
         haveTransformFromScreenToNewTarget = newTarget->renderSurface()->screenSpaceTransform().GetInverse(&inverseNewTargetScreenSpaceTransform);
 
@@ -353,7 +353,7 @@ bool OcclusionTrackerBase<LayerType, RenderSurfaceType>::occluded(const LayerTyp
     DCHECK(renderTarget->renderSurface());
     DCHECK(renderTarget == m_stack.back().target);
 
-    gfx::Transform inverseDrawTransform;
+    gfx::Transform inverseDrawTransform(gfx::Transform::kSkipInitialization);
     if (!drawTransform.GetInverse(&inverseDrawTransform))
         return false;
 
@@ -396,7 +396,7 @@ gfx::Rect OcclusionTrackerBase<LayerType, RenderSurfaceType>::unoccludedContentR
     DCHECK(renderTarget->renderSurface());
     DCHECK(renderTarget == m_stack.back().target);
 
-    gfx::Transform inverseDrawTransform;
+    gfx::Transform inverseDrawTransform(gfx::Transform::kSkipInitialization);
     if (!drawTransform.GetInverse(&inverseDrawTransform))
         return contentRect;
 
@@ -445,7 +445,7 @@ gfx::Rect OcclusionTrackerBase<LayerType, RenderSurfaceType>::unoccludedContribu
         return contentRect;
 
     gfx::Transform drawTransform = forReplica ? surface->replicaDrawTransform() : surface->drawTransform();
-    gfx::Transform inverseDrawTransform;
+    gfx::Transform inverseDrawTransform(gfx::Transform::kSkipInitialization);
     if (!drawTransform.GetInverse(&inverseDrawTransform))
         return contentRect;