Checks to prevent occasional crashes when mirroring WebXR content

Bug: 827690
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I509088a542dfc775262ae9807114db205ae6ac08
Reviewed-on: https://chromium-review.googlesource.com/988848Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Brandon Jones <bajones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548142}

third_party/WebKit/Source/modules/xr/XRWebGLLayer.cpp

@@ -125,12 +125,16 @@ XRWebGLLayer::XRWebGLLayer(XRSession* session,
   // If the contents need mirroring, indicate that to the drawing buffer.
   if (session->exclusive() && session->outputContext() &&
       session->device()->external()) {
+    mirroring_ = true;
     drawing_buffer_->SetMirrorClient(this);
   }
   UpdateViewports();
 }
 
-XRWebGLLayer::~XRWebGLLayer() {}
+XRWebGLLayer::~XRWebGLLayer() {
+  if (mirroring_)
+    drawing_buffer_->SetMirrorClient(nullptr);
+}
 
 void XRWebGLLayer::getXRWebGLRenderingContext(
     WebGLRenderingContextOrWebGL2RenderingContext& result) const {

third_party/WebKit/Source/modules/xr/XRWebGLLayer.h

@@ -99,6 +99,7 @@ class XRWebGLLayer final : public XRLayer,
   double requested_viewport_scale_ = 1.0;
   double viewport_scale_ = 1.0;
   bool viewports_dirty_ = true;
+  bool mirroring_ = false;
 };
 
 }  // namespace blink

third_party/WebKit/Source/platform/graphics/gpu/ImageLayerBridge.cpp

@@ -36,6 +36,9 @@ ImageLayerBridge::~ImageLayerBridge() {
 }
 
 void ImageLayerBridge::SetImage(scoped_refptr<StaticBitmapImage> image) {
+  if (disposed_)
+    return;
+
   image_ = std::move(image);
   if (image_) {
     if (opacity_mode_ == kNonOpaque) {
@@ -58,6 +61,9 @@ void ImageLayerBridge::SetImage(scoped_refptr<StaticBitmapImage> image) {
 
 void ImageLayerBridge::SetUV(const FloatPoint left_top,
                              const FloatPoint right_bottom) {
+  if (disposed_)
+    return;
+
   layer_->SetUV(WebFloatPoint(left_top.X(), left_top.Y()),
                 WebFloatPoint(right_bottom.X(), right_bottom.Y()));
 }