cc/blimp: Set up the framework for LayerTreeTests in remote mode.

cc/blimp/layer_tree_host_remote.cc

Index: cc/blimp/layer_tree_host_remote.cc
diff --git a/cc/blimp/layer_tree_host_remote.cc b/cc/blimp/layer_tree_host_remote.cc
index 66b7cbae8587b6a2a6920e5d3b1e41c8bb9cd396..9cc42a5efbd8477cbbfd9c72c24428696e278d24 100644
--- a/cc/blimp/layer_tree_host_remote.cc
+++ b/cc/blimp/layer_tree_host_remote.cc
@@ -424,6 +424,11 @@ void LayerTreeHostRemote::DispatchDrawAndSwapCallbacks() {
   client_->DidCompleteSwapBuffers();
 }
 
+void LayerTreeHostRemote::SetTaskRunnerProviderForTesting(
+    std::unique_ptr<TaskRunnerProvider> task_runner_provider) {
+  task_runner_provider_ = std::move(task_runner_provider);
+}
+
 void LayerTreeHostRemote::SerializeCurrentState(
     proto::LayerTreeHost* layer_tree_host_proto) {
   // We need to serialize only the inputs received from the embedder.