Use kRenderClientId command line flag when starting a render process

content/renderer/mus/compositor_mus_connection_unittest.cc

Index: content/renderer/mus/compositor_mus_connection_unittest.cc
diff --git a/content/renderer/mus/compositor_mus_connection_unittest.cc b/content/renderer/mus/compositor_mus_connection_unittest.cc
index 236bbe33ec41afefe67b3bdd75b784280037a143..d3b345a64b7326235f6f30d596add0ca598b4658 100644
--- a/content/renderer/mus/compositor_mus_connection_unittest.cc
+++ b/content/renderer/mus/compositor_mus_connection_unittest.cc
@@ -33,6 +33,8 @@ using ui::mojom::EventResult;
 
 namespace {
 
+constexpr cc::FrameSinkId kArbitraryFrameSinkId(0, 1);
+
 // Wrapper for the callback provided to
 // CompositorMusConnection:OnWindowInputEvent. This tracks whether the it was
 // called, along with the result.
@@ -155,6 +157,7 @@ class TestRenderWidget : public content::RenderWidget {
       : content::RenderWidget(compositor_deps,
                               blink::WebPopupTypeNone,
                               content::ScreenInfo(),
+                              kArbitraryFrameSinkId,
                               true,
                               false,
                               false) {}