RenderWidget: make routing_id be a parameter of the ctor

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 23e87cf27406508236b8a932154666690a27194c..9aa7ebcb49c86beea225b0bd41abaceea627ce13 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -658,7 +658,8 @@ class AlwaysDrawSwapPromise : public cc::SwapPromise {
 
 RenderViewImpl::RenderViewImpl(CompositorDependencies* compositor_deps,
                                const mojom::CreateViewParams& params)
-    : RenderWidget(compositor_deps,
+    : RenderWidget(params.view_id,
+                   compositor_deps,
                    blink::WebPopupTypeNone,
                    params.initial_size.screen_info,
                    params.swapped_out,
@@ -697,7 +698,7 @@ RenderViewImpl::RenderViewImpl(CompositorDependencies* compositor_deps,
 
 void RenderViewImpl::Initialize(const mojom::CreateViewParams& params,
                                 bool was_created_by_renderer) {
-  RenderWidget::InitRoutingID(params.view_id);
+  RenderWidget::InitInputHandler();

[lfg, 2016/11/14 22:09:59]

Why do you need to add this? I assume tests were failing. Can you add a comment
explaining?

[ncarter (slow), 2016/11/14 23:33:56]

It wasn't strictly necessary; I figured that so long as I had InitInputHandler()
around, I could preserve the old ordering in case there was any unseen
dependency between WebView::create(this) and the input handler.

However, I went back and figured out the render_widget_unittest situation, which
was a leak due to an unbalanced bare AddRef(). So now, InitInputHandler is gone
again.

 
   int opener_view_routing_id = MSG_ROUTING_NONE;
   WebFrame* opener_frame = RenderFrameImpl::ResolveOpener(