mustash: Remove NOTREACHED() so navigation does not crash

content/browser/renderer_host/render_widget_host_view_mus.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_view_mus.h"
 
 #include "components/mus/public/cpp/window.h"
 #include "components/mus/public/cpp/window_tree_connection.h"
 #include "content/browser/mojo/mojo_shell_client_host.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
@@ skipping 184 matching lines @@
 
 void RenderWidgetHostViewMus::SetBackgroundColor(SkColor color) {
   // TODO(fsamuel): Implement background color and opacity.
 }
 
 void RenderWidgetHostViewMus::CopyFromCompositingSurface(
     const gfx::Rect& /* src_subrect */,
     const gfx::Size& /* dst_size */,
     const ReadbackRequestCallback& callback,
     const SkColorType /* preferred_color_type */) {
-  NOTREACHED();
+  // TODO(fsamuel): Implement read back.
+  NOTIMPLEMENTED();
   callback.Run(SkBitmap(), READBACK_FAILED);
 }
 
 void RenderWidgetHostViewMus::CopyFromCompositingSurfaceToVideoFrame(
     const gfx::Rect& src_subrect,
     const scoped_refptr<media::VideoFrame>& target,
     const base::Callback<void(const gfx::Rect&, bool)>& callback) {
   NOTIMPLEMENTED();
   callback.Run(gfx::Rect(), false);
 }
@@ skipping 85 matching lines @@
 void RenderWidgetHostViewMus::SetParentNativeViewAccessible(
     gfx::NativeViewAccessible accessible_parent) {}
 
 gfx::NativeViewId RenderWidgetHostViewMus::GetParentForWindowlessPlugin()
     const {
   return gfx::NativeViewId();
 }
 #endif
 
 }  // namespace content