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 8be87ea534e50001aea2e9176ce6b34c0ebfb4a5..6474b40ab97c121deec22ceeceb4b157f71711ae 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
@@ -4,18 +4,22 @@
 
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
 
+#include "base/command_line.h"
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_manager.h"
 #include "cc/surfaces/surface_sequence.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "content/browser/browser_plugin/browser_plugin_guest.h"
 #include "content/browser/compositor/surface_utils.h"
 #include "content/browser/frame_host/cross_process_frame_connector.h"
 #include "content/browser/gpu/compositor_util.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"
 #include "content/public/browser/render_process_host.h"
+#include "content/public/common/content_switches.h"
 
 namespace content {
 
@@ -151,6 +155,18 @@ void RenderWidgetHostViewChildFrame::UpdateCursor(const WebCursor& cursor) {
 }
 
 void RenderWidgetHostViewChildFrame::SetIsLoading(bool is_loading) {
+  // It is valid for an inner WebContents's SetIsLoading() to end up here.
+  // This is because an inner WebContents's main frame's widget host view is a

[nasko, 2015/06/23 13:39:23]

nit: Let's avoid using "widget host view" and use the actual object name. It is
not as pretty because of the longish string, but it is actually more accurate
and we should aim for that.

[lazyboy, 2015/06/23 23:00:00]

Done.

+  // RenderWidgetHostViewChildFrame. In contrast, when there is no inner/outer
+  // WebContents, only subframe's widget host view can be a
+  // RenderWidgetHostViewChildFrame which do not get a SetIsLoading() call.
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kSitePerProcess) &&
+      BrowserPluginGuest::IsGuest(
+          static_cast<RenderViewHostImpl*>(RenderViewHost::From(host_)))) {
+    return;
+  }
+
   NOTREACHED();
 }