Remove cc::LayerTreeHostImpl::IsContextLost

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index f04a96cc1ee008b738d9d06839497a317f7ea1fc..5f5f5f88618c62b6f73a91e603b981c1f5915a2b 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -257,7 +257,6 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
       micro_benchmark_controller_(this),
       need_to_update_visible_tiles_before_draw_(false),
-      have_valid_output_surface_(false),
       shared_bitmap_manager_(manager),
       id_(id),
       transfer_buffer_memory_limit_(0u) {
@@ -1616,13 +1615,6 @@ void LayerTreeHostImpl::FinishAllRendering() {
     renderer_->Finish();
 }
 
-bool LayerTreeHostImpl::IsContextLost() {
-  DCHECK(proxy_->IsImplThread());
-  // To avoid races, rely only on the lost-surface callback.
-  // See crbug.com/392891.
-  return !have_valid_output_surface_;
-}
-
 void LayerTreeHostImpl::SetUseGpuRasterization(bool use_gpu) {
   if (use_gpu == use_gpu_rasterization_)
     return;
@@ -1725,9 +1717,6 @@ float LayerTreeHostImpl::VerticalAdjust() const {
 }
 
 void LayerTreeHostImpl::DidLoseOutputSurface() {
-  if (!have_valid_output_surface_)
-    return;
-  have_valid_output_surface_ = false;
   if (resource_provider_)
     resource_provider_->DidLoseOutputSurface();
   // TODO(jamesr): The renderer_ check is needed to make some of the
@@ -2098,7 +2087,6 @@ bool LayerTreeHostImpl::InitializeRenderer(
     return false;
 
   output_surface_ = output_surface.Pass();
-  have_valid_output_surface_ = true;
   resource_provider_ =
       ResourceProvider::Create(output_surface_.get(),
                                shared_bitmap_manager_,