Implement desktop compatibility viewport

cc/layer_tree_host_common.cc

Index: cc/layer_tree_host_common.cc
diff --git a/cc/layer_tree_host_common.cc b/cc/layer_tree_host_common.cc
index 7c559b7420b180ae1c09b92751505c04aa62d82e..7cb27044781b2d6f742dba68e427480611e474ef 100644
--- a/cc/layer_tree_host_common.cc
+++ b/cc/layer_tree_host_common.cc
@@ -338,6 +338,16 @@ gfx::Transform computeScrollCompensationForThisLayer(LayerImpl* scrollingLayer,
     gfx::Transform scrollCompensationForThisLayer = partialLayerOriginTransform; // Step 3
     scrollCompensationForThisLayer.Translate(scrollingLayer->scrollDelta().x(), scrollingLayer->scrollDelta().y()); // Step 2
 
+    gfx::Vector2dF desktopCompatibilityViewportDelta = scrollingLayer->desktopCompatibilityViewportOffsetFromScrollPositionDelta();
+    scrollCompensationForThisLayer.Translate(desktopCompatibilityViewportDelta.x(), desktopCompatibilityViewportDelta.y());
+
+    {
+        gfx::Vector2dF tmp = scrollingLayer->desktopCompatibilityViewportOffsetFromScrollPosition();
+        gfx::Vector2dF tmp2 = scrollingLayer->desktopCompatibilityViewportOffsetFromScrollPositionDelta();
+        fprintf (stderr, "offset: %f %f\n", tmp.x(), tmp.y());
+        fprintf (stderr, "delta : %f %f\n", tmp2.x(), tmp2.y());
+    }
+
     gfx::Transform inversePartialLayerOriginTransform(gfx::Transform::kSkipInitialization);
     if (!partialLayerOriginTransform.GetInverse(&inversePartialLayerOriginTransform)) {
         // TODO(shawnsingh): Either we need to handle uninvertible transforms