Initial viewport is not the same as FrameView rect.

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

Index: third_party/WebKit/Source/core/css/MediaValuesInitialViewport.cpp
diff --git a/third_party/WebKit/Source/core/css/MediaValuesInitialViewport.cpp b/third_party/WebKit/Source/core/css/MediaValuesInitialViewport.cpp
index 0d9f776cd3dc65b6f77ac90dee16ac14a5c683db..8ed02280cdb46f52ffe8f4cdb89aaab0578e15b6 100644
--- a/third_party/WebKit/Source/core/css/MediaValuesInitialViewport.cpp
+++ b/third_party/WebKit/Source/core/css/MediaValuesInitialViewport.cpp
@@ -19,17 +19,13 @@ MediaValuesInitialViewport::MediaValuesInitialViewport(LocalFrame& frame)
     : MediaValuesDynamic(&frame) {}
 
 double MediaValuesInitialViewport::viewportWidth() const {
-  DCHECK(m_frame->view() && m_frame->document());
-  int viewportWidth = m_frame->view()->frameRect().width();
-  return adjustDoubleForAbsoluteZoom(
-      viewportWidth, m_frame->document()->layoutViewItem().styleRef());
+  DCHECK(m_frame->view());
+  return m_frame->view()->initialViewportWidth();

[bokan, 2016/10/18 17:19:26]

I'm a stranger around these parts, but m_frame can be an iframe, right? I don't
see where we set the initialViewport size for non-main frames.

[rune, 2016/10/18 22:09:53]

Right, MediaValuesInitialViewport are only used for @viewport descriptors and
@media evaluation for collecting @viewport rules.

@viewport rules are only collected for main frames. That is, they will only be
collected for main frames after [1]. Before [1] they are collected, but setting
the viewport description has no effect since we're checking for main frame
before doing anything with it.

It would be more consistent if we initialized FrameView's initialViewportSize
for non-main frames as well?

Or perhaps DCHECKs for being called from a main frame?

[1] https://codereview.chromium.org/2420413005/

[bokan, 2016/10/18 22:28:06]

Ok. I'm fine with either approach though DCHECKs for main frame are probably
better since we don't expect initialViewport to be used from iframes for now.

[rune, 2016/10/18 22:56:12]

DCHECKs added.

 }
 
 double MediaValuesInitialViewport::viewportHeight() const {
-  DCHECK(m_frame->view() && m_frame->document());
-  int viewportHeight = m_frame->view()->frameRect().height();
-  return adjustDoubleForAbsoluteZoom(
-      viewportHeight, m_frame->document()->layoutViewItem().styleRef());
+  DCHECK(m_frame->view());
+  return m_frame->view()->initialViewportHeight();
 }
 
 }  // namespace blink