Route touch-events for WebViewGuest directly to guest renderer.

content/browser/frame_host/render_widget_host_view_child_frame.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_widget_host_view_child_frame.h"
 
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_manager.h"
 #include "cc/surfaces/surface_sequence.h"
@@ skipping 15 matching lines @@
 
 namespace content {
 
 RenderWidgetHostViewChildFrame::RenderWidgetHostViewChildFrame(
     RenderWidgetHost* widget_host)
     : host_(RenderWidgetHostImpl::From(widget_host)),
       use_surfaces_(UseSurfacesEnabled()),
       next_surface_sequence_(1u),
       last_output_surface_id_(0),
       current_surface_scale_factor_(1.f),
+      has_started_rendering_(false),
       ack_pending_count_(0),
       frame_connector_(nullptr),
       weak_factory_(this) {
-  if (use_surfaces_) {
+  if (use_surfaces_)
     id_allocator_ = CreateSurfaceIdAllocator();
-    if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
-      host_->delegate()->GetInputEventRouter()->AddSurfaceIdNamespaceOwner(
-          GetSurfaceIdNamespace(), this);
-    }
-  }
 
   host_->SetView(this);
 }
 
 RenderWidgetHostViewChildFrame::~RenderWidgetHostViewChildFrame() {
   if (!surface_id_.is_null())
     surface_factory_->Destroy(surface_id_);
 }
 
 void RenderWidgetHostViewChildFrame::InitAsChild(
@@ skipping 204 matching lines @@
   // the embedder's renderer to be composited.
   if (!frame->delegated_frame_data || !use_surfaces_) {
     frame_connector_->ChildFrameCompositorFrameSwapped(
         output_surface_id,
         host_->GetProcess()->GetID(),
         host_->GetRoutingID(),
         frame.Pass());
     return;
   }
 
+  if (!has_started_rendering_) {
+    if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
+      host_->delegate()->GetInputEventRouter()->AddSurfaceIdNamespaceOwner(

[tdresser, 2015/11/02 15:38:24]

It isn't clear to me why this was postponed - is it a performance optimization,
or was there a correctness issue?

[kenrb, 2015/11/02 16:04:22]

I don't really like this, but I understand why it is here and don't
immedatiately see a better alternative. I think it is that the inner WebContents
for the guestview isn't attached to the outer WebContents at the point that this
is created, so it is not able to register the surfaceID namespace with the
correct RenderWidgetHostInputEventRouter.

The current code registers it as soon as the surfaceID is created, which is
better, but I don't know how else to do this.

[wjmaclean, 2015/11/02 19:23:10]

I suppose one alternative would be to leave this registration in the
constructor, then have WebViewGuest *de-register* and then re-register at time
of first swap ... I *think* that would work, though we'd have to consider it an
experiment. I'm not sure how it would affect the RWHVA that's attached to the
RWHVG.

[tdresser, 2015/11/02 21:10:19]

This seems reasonable to me.

+          GetSurfaceIdNamespace(), this);
+    }
+    has_started_rendering_ = true;
+  }
+
   cc::RenderPass* root_pass =
       frame->delegated_frame_data->render_pass_list.back();
 
   gfx::Size frame_size = root_pass->output_rect.size();
   float scale_factor = frame->metadata.device_scale_factor;
 
   // Check whether we need to recreate the cc::Surface, which means the child
   // frame renderer has changed its output surface, or size, or scale factor.
   if (output_surface_id != last_output_surface_id_ && surface_factory_) {
     surface_factory_->Destroy(surface_id_);
@@ skipping 196 matching lines @@
       BrowserAccessibilityManager::GetEmptyDocument(), delegate);
 }
 
 void RenderWidgetHostViewChildFrame::ClearCompositorSurfaceIfNecessary() {
   if (surface_factory_ && !surface_id_.is_null())
     surface_factory_->Destroy(surface_id_);
   surface_id_ = cc::SurfaceId();
 }
 
 }  // namespace content