Re-route Touchscreen GesturePinch events to root view.

content/browser/renderer_host/render_widget_host_input_event_router.cc

Index: content/browser/renderer_host/render_widget_host_input_event_router.cc
diff --git a/content/browser/renderer_host/render_widget_host_input_event_router.cc b/content/browser/renderer_host/render_widget_host_input_event_router.cc
index 9786dad6d20708b7de81d7cef93b633ac84dfe5b..9651f281242bcc82dafe6cb522ab668da51b0f1d 100644
--- a/content/browser/renderer_host/render_widget_host_input_event_router.cc
+++ b/content/browser/renderer_host/render_widget_host_input_event_router.cc
@@ -95,7 +95,7 @@ bool RenderWidgetHostInputEventRouter::HittestDelegate::AcceptHitTarget(
 }
 
 RenderWidgetHostInputEventRouter::RenderWidgetHostInputEventRouter()
-    : active_touches_(0) {}
+    : active_touches_(0), in_touchscreen_gesture_pinch_(false) {}
 
 RenderWidgetHostInputEventRouter::~RenderWidgetHostInputEventRouter() {
   // We may be destroyed before some of the owners in the map, so we must
@@ -312,7 +312,8 @@ void RenderWidgetHostInputEventRouter::BubbleScrollEvent(
 void RenderWidgetHostInputEventRouter::SendGestureScrollBegin(
     RenderWidgetHostViewBase* view,
     const blink::WebGestureEvent& event) {
-  DCHECK(event.type == blink::WebInputEvent::GestureScrollUpdate);
+  DCHECK(event.type == blink::WebInputEvent::GestureScrollUpdate ||
+         event.type == blink::WebInputEvent::GesturePinchBegin);
   blink::WebGestureEvent scroll_begin(event);
   scroll_begin.type = blink::WebInputEvent::GestureScrollBegin;
   scroll_begin.data.scrollBegin.deltaXHint = event.data.scrollUpdate.deltaX;
@@ -325,7 +326,8 @@ void RenderWidgetHostInputEventRouter::SendGestureScrollBegin(
 void RenderWidgetHostInputEventRouter::SendGestureScrollEnd(
     RenderWidgetHostViewBase* view,
     const blink::WebGestureEvent& event) {
-  DCHECK(event.type == blink::WebInputEvent::GestureScrollUpdate);
+  DCHECK(event.type == blink::WebInputEvent::GestureScrollUpdate ||
+         event.type == blink::WebInputEvent::GesturePinchEnd);
   blink::WebGestureEvent scroll_end(event);
   scroll_end.type = blink::WebInputEvent::GestureScrollEnd;
   scroll_end.timeStampSeconds =
@@ -386,6 +388,29 @@ void RenderWidgetHostInputEventRouter::RouteTouchscreenGestureEvent(
     const ui::LatencyInfo& latency) {
   DCHECK_EQ(blink::WebGestureDeviceTouchscreen, event->sourceDevice);
 
+  if (event->type == blink::WebInputEvent::GesturePinchBegin) {
+    in_touchscreen_gesture_pinch_ = true;
+    // If the root view wasn't already receiving the gesture stream, then we
+    // need to wrap the diverted pinch events in a GestureScrollBegin/End.
+    // TODO(wjmaclean,kenrb,tdresser): When scroll latching lands, we can
+    // revisit how this code should work.
+    // https://crbug.com/526463
+    if (root_view != touchscreen_gesture_target_.target)
+      SendGestureScrollBegin(root_view, *event);
+  }
+
+  if (in_touchscreen_gesture_pinch_) {
+    root_view->ProcessGestureEvent(*event, latency);
+    if (event->type == blink::WebInputEvent::GesturePinchEnd) {
+      in_touchscreen_gesture_pinch_ = false;
+      // If the root view wasn't already receiving the gesture stream, then we
+      // need to wrap the diverted pinch events in a GestureScrollBegin/End.
+      if (root_view != touchscreen_gesture_target_.target)
+        SendGestureScrollEnd(root_view, *event);
+    }
+    return;
+  }
+
   // We use GestureTapDown to detect the start of a gesture sequence since there
   // is no WebGestureEvent equivalent for ET_GESTURE_BEGIN. Note that this
   // means the GestureFlingCancel that always comes between ET_GESTURE_BEGIN and