Propagate inert state to OOPIFs when a modal dialog is active

content/browser/frame_host/render_widget_host_view_child_frame.cc

Index: content/browser/frame_host/render_widget_host_view_child_frame.cc
diff --git a/content/browser/frame_host/render_widget_host_view_child_frame.cc b/content/browser/frame_host/render_widget_host_view_child_frame.cc
index 59efca167892939fc60e02cc0a8925b1b11c5145..f4766ca2a7165b9c6b0a1650927a522703e2f44d 100644
--- a/content/browser/frame_host/render_widget_host_view_child_frame.cc
+++ b/content/browser/frame_host/render_widget_host_view_child_frame.cc
@@ -383,6 +383,13 @@ void RenderWidgetHostViewChildFrame::UpdateViewportIntersection(
                                                     viewport_intersection));
 }
 
+void RenderWidgetHostViewChildFrame::SetIsInert() {
+  if (host_ && frame_connector_) {
+    host_->Send(new ViewMsg_SetIsInert(host_->GetRoutingID(),
+                                       frame_connector_->is_inert()));
+  }
+}
+
 void RenderWidgetHostViewChildFrame::GestureEventAck(
     const blink::WebGestureEvent& event,
     InputEventAckState ack_result) {
@@ -620,8 +627,10 @@ bool RenderWidgetHostViewChildFrame::IsRenderWidgetHostViewChildFrame() {
 }
 
 void RenderWidgetHostViewChildFrame::WillSendScreenRects() {
-  if (frame_connector_)
+  if (frame_connector_) {
     UpdateViewportIntersection(frame_connector_->viewport_intersection());
+    SetIsInert();

[alexmos, 2017/06/20 18:46:10]

Assuming that this handles the new process case, it seems like this will send
the inert IPC more often than necessary (every time there's a screen rects
update) - or maybe there's another reason why that's needed here and not
somewhere like Init()?  See also my earlier question about whether this will
work for cases like a(b(b)) and the bottom child navigating to a new process.

[kenrb, 2017/06/22 15:33:35]

I agree this doesn't feel like the greatest place, but I don't see a better one
for either SetIsInert or UpdateViewportIntersection, which need to trigger at a
certain point after cross-process navigations (this is covering a(b) -> a(c)
navigation scenario). RWHVCF::Init() is too early in terms of renderer state.
This will send the IPC unnecessarily, sometimes, but it doesn't get called very
often so it shouldn't be too bad. There are definitely some improvements that
can be made to RWHVCF initialization, so this might be re-thought when we get
around to dealing with subframe vs top-level frame resizing (bug 618353).

As mentioned in the other response, a(b(b)) -> a(b(c)) is covered by Blink
initializing the RemoteFrame.

[alexmos, 2017/06/22 17:09:27]

OK.  Perhaps add a TODO and describe some of those concerns here?

+  }
 }
 
 #if defined(OS_MACOSX)