Make <webview> use out-of-process iframe architecture.

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 b8fdb0193d5800ad2867f95a5c1dc74014bf1828..b68f961f0f1441b282513355a26f0b3ad2ff4ccb 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
@@ -5,7 +5,9 @@
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
 
 #include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "content/browser/browser_plugin/browser_plugin_guest.h"
 #include "content/browser/frame_host/cross_process_frame_connector.h"
+#include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/view_messages.h"
@@ -134,7 +136,10 @@ void RenderWidgetHostViewChildFrame::UpdateCursor(const WebCursor& cursor) {
 }
 
 void RenderWidgetHostViewChildFrame::SetIsLoading(bool is_loading) {
-  NOTREACHED();
+  if (!BrowserPluginGuest::IsGuest(static_cast<RenderViewHostImpl*>(

[Charlie Reis, 2015/05/22 23:44:31]

This needs a comment.  I'm also confused, since it seems backwards.  Won't
IsGuest be true in the default <webview> flow, causing us to skip the
NOTREACHED?  And is it false in --site-per-process, in which case we hit the
NOTREACHED?  What was the intention?

[lazyboy, 2015/05/26 16:32:54]

default webview does not hit this function.
I think is_loading is broken in this CL as you've pointed
out in the Swap IPC.

+          RenderViewHost::From(host_)))) {
+    NOTREACHED();
+  }
 }
 
 void RenderWidgetHostViewChildFrame::TextInputTypeChanged(