Propagate auto-resize viewport values to OOPIF processes

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index ed882eff1d6c293bf29985766f4031d368b948c8..e2e7c50965f7278c35bc4f0d901be2e647109d7f 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -2786,10 +2786,28 @@ void WebContentsImpl::ResizeDueToAutoResize(
   if (render_widget_host != GetRenderViewHost()->GetWidget())
     return;
 
+  auto_resize_size_ = new_size;
+
+  // Out-of-process iframe visible viewport sizes usually come from the
+  // top-level RenderWidgetHostView, but when auto-resize is enabled on the
+  // top frame then that size is used instead.
+  for (FrameTreeNode* node : frame_tree_.Nodes()) {
+    if (node->current_frame_host()->is_local_root()) {
+      RenderWidgetHostImpl* host =
+          node->current_frame_host()->GetRenderWidgetHost();
+      if (host != render_widget_host)
+        host->SendScreenRects();

[alexmos, 2017/06/02 17:03:18]

Just to make sure I understand: how does this end up using |new_size|? 
SendScreenRects() seems to send  GetViewBounds() and GetBoundsInRootWindow() -
do those end up depending on the auto-resize size and querying
GetAutoResizeSize() somehow?

[kenrb, 2017/06/02 17:23:27]

Good catch, thanks, this is wrong. I had mistakenly thought that there was
SendScreenRects also activated the RWHI resize path, but it doesn't. The fact
that it worked was probably a fluke, that auto-size was always getting activated
early enough for this not to matter.

Now corrected.

+    }
+  }
+
   if (delegate_)
     delegate_->ResizeDueToAutoResize(this, new_size);
 }
 
+gfx::Size WebContentsImpl::GetAutoResizeSize() {
+  return auto_resize_size_;
+}
+
 WebContents* WebContentsImpl::OpenURL(const OpenURLParams& params) {
   if (!delegate_)
     return NULL;