aura: Some change to how the client-lib is set up.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 0e25e8ef40995d9cbded658872ece04900b0534f..add7bda29e3a2d1a0a5783addf4298ae571553aa 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -288,6 +288,7 @@
 #if defined(USE_AURA)
 #include "services/service_manager/runner/common/client_util.h"
 #include "services/ui/public/cpp/gpu/gpu.h"
+#include "ui/aura/mus/window_tree_client.h"
 #include "ui/views/mus/mus_client.h"
 #endif
 
@@ -2706,7 +2707,7 @@ gpu::GpuChannelEstablishFactory*
 ChromeContentBrowserClient::GetGpuChannelEstablishFactory() {
 #if defined(USE_AURA)
   if (views::MusClient::Exists())
-    return views::MusClient::Get()->gpu();
+    return views::MusClient::Get()->window_tree_client()->gpu();
 #endif
   return nullptr;
 }