viz/mac: Update SetShowPrimarySurface after navigation

After navigation, the surface id changes, but no call is made to
SetShowPrimarySurface, to tell the ui::Compositor to draw this
surface. Add a call to DelegatedFrameHost::WasResized to cause
this to happen.

Bug: 772576
Change-Id: I33e1fd509e3666f07a4f9a86aa600dc54adac733
Reviewed-on: https://chromium-review.googlesource.com/894197
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: Saman Sami <samans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533847}

content/browser/renderer_host/browser_compositor_view_mac.mm

@@ -575,6 +575,7 @@ void BrowserCompositorMac::DidNavigate() {
   delegated_frame_host_surface_id_ =
       parent_local_surface_id_allocator_.GenerateId();
   delegated_frame_host_->DidNavigate();
+  delegated_frame_host_->WasResized(cc::DeadlinePolicy::UseExistingDeadline());
 }
 
 void BrowserCompositorMac::DidReceiveFirstFrameAfterNavigation() {