Fix initialization in MusBrowserCompositorOutputSurface

Wasn't nulling out a couple of fields.

BUG=672932
TEST=none
R=fsamuel@chromium.org, jbauman@chromium.org

Review-Url: https://codereview.chromium.org/2570603002
Cr-Commit-Position: refs/heads/master@{#438035}

content/browser/compositor/OWNERS

@@ -2,6 +2,6 @@ danakj@chromium.org
 jbauman@chromium.org
 ccameron@chromium.org
 
-per-file *Mus*=fsamuel@chromium.org
-per-file *Mus*=sadrul@chromium.org
-per-file *Mus*=rjkroege@chromium.org
+per-file *mus*=fsamuel@chromium.org
+per-file *mus*=sadrul@chromium.org
+per-file *mus*=rjkroege@chromium.org

content/browser/compositor/mus_browser_compositor_output_surface.cc

@@ -32,7 +32,8 @@ MusBrowserCompositorOutputSurface::MusBrowserCompositorOutputSurface(
     : GpuBrowserCompositorOutputSurface(std::move(context),
                                         update_vsync_parameters_callback,
                                         std::move(overlay_candidate_validator)),
-      ui_window_(window) {
+      ui_window_(window),
+      window_(nullptr) {
   ui_compositor_frame_sink_ = ui_window_->RequestCompositorFrameSink(
       ui::mojom::CompositorFrameSinkType::DEFAULT, context,
       gpu_memory_buffer_manager);
@@ -49,6 +50,7 @@ MusBrowserCompositorOutputSurface::MusBrowserCompositorOutputSurface(
     : GpuBrowserCompositorOutputSurface(std::move(context),
                                         update_vsync_parameters_callback,
                                         std::move(overlay_candidate_validator)),
+      ui_window_(nullptr),
       window_(window) {
   aura::WindowPortMus* window_port = aura::WindowPortMus::Get(window_);
   DCHECK(window_port);