cc: Make single-thread renderer compositor always synchronous.

cc/trees/layer_tree_host_unittest_context.cc

Index: cc/trees/layer_tree_host_unittest_context.cc
diff --git a/cc/trees/layer_tree_host_unittest_context.cc b/cc/trees/layer_tree_host_unittest_context.cc
index 670ae8a14e66af766b1bd2e81511828fc58f17fb..c8bb8f097ac8040eb1ff27588cfae1eb2154e05b 100644
--- a/cc/trees/layer_tree_host_unittest_context.cc
+++ b/cc/trees/layer_tree_host_unittest_context.cc
@@ -385,6 +385,7 @@ class MultipleCompositeDoesNotCreateOutputSurface
 
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->single_thread_proxy_scheduler = false;
+    settings->use_zero_copy = true;
   }
 
   void RequestNewOutputSurface() override {
@@ -422,6 +423,7 @@ class FailedCreateDoesNotCreateExtraOutputSurface
 
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->single_thread_proxy_scheduler = false;
+    settings->use_zero_copy = true;
   }
 
   void RequestNewOutputSurface() override {
@@ -473,6 +475,7 @@ class LayerTreeHostContextTestCommitAfterDelayedOutputSurface
 
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->single_thread_proxy_scheduler = false;
+    settings->use_zero_copy = true;
   }
 
   void RequestNewOutputSurface() override {
@@ -512,6 +515,7 @@ class LayerTreeHostContextTestAvoidUnnecessaryComposite
 
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->single_thread_proxy_scheduler = false;
+    settings->use_zero_copy = true;
   }
 
   void RequestNewOutputSurface() override {