Initial containing block for print not affected by page zoom.

third_party/WebKit/Source/core/css/MediaValues.cpp

Index: third_party/WebKit/Source/core/css/MediaValues.cpp
diff --git a/third_party/WebKit/Source/core/css/MediaValues.cpp b/third_party/WebKit/Source/core/css/MediaValues.cpp
index c35e2947008f95623fe44b683c5b502d28847eb7..a9248b18b6f7c6097d8a53b92b061dc333cd2f3c 100644
--- a/third_party/WebKit/Source/core/css/MediaValues.cpp
+++ b/third_party/WebKit/Source/core/css/MediaValues.cpp
@@ -32,16 +32,12 @@ MediaValues* MediaValues::createDynamicIfFrameExists(LocalFrame* frame) {
 
 double MediaValues::calculateViewportWidth(LocalFrame* frame) {
   ASSERT(frame && frame->view() && frame->document());
-  int viewportWidth = frame->view()->layoutSize(IncludeScrollbars).width();
-  return adjustDoubleForAbsoluteZoom(
-      viewportWidth, frame->document()->layoutViewItem().styleRef());
+  return frame->view()->viewportSizeForViewportUnits().width();
 }
 
 double MediaValues::calculateViewportHeight(LocalFrame* frame) {
   ASSERT(frame && frame->view() && frame->document());
-  int viewportHeight = frame->view()->layoutSize(IncludeScrollbars).height();
-  return adjustDoubleForAbsoluteZoom(
-      viewportHeight, frame->document()->layoutViewItem().styleRef());
+  return frame->view()->viewportSizeForViewportUnits().height();

[bokan, 2017/03/09 16:29:56]

I think this is slightly wrong. The reason we have a specific viewportSize for
ViewportUnits is because 100vh is actually taller than the ICB by the height of
the URL bar and I think Media Queries should really report the ICB. I would
either add a zoomedLayoutSize method on FrameView or keep the zoom logic in
here.

[rune, 2017/03/09 17:47:36]

Why is there a difference between ICB and viewport units? The documentation says
it's in order to match Safari. Is that the only reason? 100% height relative to
the ICB is different from 100vh in Chromium, which is strange:

http://jsbin.com/bepejugowu/1/edit?html,css,js,output

Based on that jsbin snippet vh is relative to the whole screen while the ICB is
relative to the available space without the URL-bar. I noticed that layout ng is
actually using viewportSizeForViewportUnits for its constraint space. That would
be different from the current code afaict?

[rune, 2017/03/09 22:04:55]

I added a new viewportSizeForMediaQueries() instead.

 }
 
 int MediaValues::calculateDeviceWidth(LocalFrame* frame) {