Route touch-events for WebViewGuest directly to guest renderer.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index fd2a94cc979e71b8b871e920f7832448e75735c9..6a1d012a6e95094b6fa4b1d1406b24ad4b23f49e 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -45,6 +45,7 @@
 #include "content/browser/renderer_host/web_input_event_aura.h"
 #include "content/common/gpu/client/gl_helper.h"
 #include "content/common/gpu/gpu_messages.h"
+#include "content/common/site_isolation_policy.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/overscroll_configuration.h"
@@ -857,6 +858,19 @@ bool RenderWidgetHostViewAura::CanRendererHandleEvent(
   return true;
 }
 
+bool RenderWidgetHostViewAura::ShouldRouteEvent(const ui::Event* event) const {
+  // We should route an event in two cases:
+  // 1) If cross-process frames are possible, then we route the event.

[Charlie Reis, 2015/12/10 21:58:14]

This doesn't seem to be what the code below is doing.  The comment makes it
sound like "cross-process frames are possible" implies "route the event."  The
code below doesn't seem to take AreCrossProcessFramesPossible into account
unless |result| is true, in which case *both* |result| and
AreCrossProcessFramesPossible need to be true.

[wjmaclean, 2015/12/10 22:44:14]

Perhaps I've badly worded the comment. Prior to this CL we only checked if the
IER exists, as that is gated on AreCrossProcessFramesPossible. It also only
handled mouse/wheel events.

This CL changes it so the IER is always created, but we still don't route
mouse/wheel events if AreCrossProcessFramesPossible is false. But we do always
route touch events.

+  // 2) Even if (1) is not satisfied, we still route the event if we have
+  //    an input event router: at present this only happens for touch events,
+  //    and is required in order that pinch-zoom works properly for
+  //    WebViews.
+  bool result = host_->delegate() && host_->delegate()->GetInputEventRouter();

[Charlie Reis, 2015/12/10 21:58:15]

This looks like it will almost always be true (unless the tab is being
destroyed), due to the change to WebContents.

[wjmaclean, 2015/12/10 22:44:14]

Yes. But |result| can be set false if we are dealing with a mouse/wheel event,
and --site-per-process isn't on.

+  if (event->IsMouseEvent())
+    result = result && SiteIsolationPolicy::AreCrossProcessFramesPossible();

[Charlie Reis, 2015/12/10 21:58:15]

On a related note, we should confirm whether AreCrossProcessFramesPossible is
the right thing to be checking here.

In the near future, we'll likely be turning on --isolate-extensions by default,
which means AreCrossProcessFramesPossible will always return true (since there
will be OOPIFs for web iframes inside extensions).  --site-per-process mode is
still further out.

Is that what you'd expect?  Are there blocking issues here before we turn that
on by default?

[wjmaclean, 2015/12/10 22:44:14]

OK. This code is based on the existing logic, so if it's wrong in this CL, then
I suspect it's also wrong in the existing code.
I certainly wouldn't expect the IER to be enable for all RWHVA's with just
--isolate-extensions, so perhaps AreCrossProcessFramesPossible is wrong, but
then (as mentioned above) I think it's also wrong for the existing logic.

+  return result;
+}
+
 void RenderWidgetHostViewAura::HandleParentBoundsChanged() {
   SnapToPhysicalPixelBoundary();
 #if defined(OS_WIN)
@@ -2127,7 +2141,7 @@ void RenderWidgetHostViewAura::OnMouseEvent(ui::MouseEvent* event) {
     blink::WebMouseWheelEvent mouse_wheel_event =
         MakeWebMouseWheelEvent(static_cast<ui::MouseWheelEvent&>(*event));
     if (mouse_wheel_event.deltaX != 0 || mouse_wheel_event.deltaY != 0) {
-      if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
+      if (ShouldRouteEvent(event)) {
         host_->delegate()->GetInputEventRouter()->RouteMouseWheelEvent(
             this, &mouse_wheel_event);
       } else {
@@ -2146,7 +2160,7 @@ void RenderWidgetHostViewAura::OnMouseEvent(ui::MouseEvent* event) {
 
       blink::WebMouseEvent mouse_event = MakeWebMouseEvent(*event);
       ModifyEventMovementAndCoords(&mouse_event);
-      if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
+      if (ShouldRouteEvent(event)) {
         host_->delegate()->GetInputEventRouter()->RouteMouseEvent(this,
                                                                   &mouse_event);
       } else {
@@ -2219,6 +2233,12 @@ void RenderWidgetHostViewAura::ProcessMouseWheelEvent(
   host_->ForwardWheelEvent(event);
 }
 
+void RenderWidgetHostViewAura::ProcessTouchEvent(
+    const blink::WebTouchEvent& event,
+    const ui::LatencyInfo& latency) {
+  host_->ForwardTouchEventWithLatencyInfo(event, latency);
+}
+
 void RenderWidgetHostViewAura::TransformPointToLocalCoordSpace(
     const gfx::Point& point,
     cc::SurfaceId original_surface,
@@ -2293,7 +2313,12 @@ void RenderWidgetHostViewAura::OnTouchEvent(ui::TouchEvent* event) {
   // Set unchanged touch point to StateStationary for touchmove and
   // touchcancel to make sure only send one ack per WebTouchEvent.
   MarkUnchangedTouchPointsAsStationary(&touch_event, event->touch_id());
-  host_->ForwardTouchEventWithLatencyInfo(touch_event, *event->latency());
+  if (ShouldRouteEvent(event)) {
+    host_->delegate()->GetInputEventRouter()->RouteTouchEvent(
+        this, &touch_event, *event->latency());
+  } else {
+    ProcessTouchEvent(touch_event, *event->latency());
+  }
 }
 
 void RenderWidgetHostViewAura::OnGestureEvent(ui::GestureEvent* event) {