cc: Use correct message loop proxy in BlockingTaskRunner

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index 688937eda3a8f15fc3e0daf9c8452d84926f0bbe..d1cb6d13033849fd374fc9e98c15364a99fe2e80 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -202,7 +202,8 @@ void ThreadProxy::DidLoseOutputSurface() {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
 
     // Return lost resources to their owners immediately.
-    BlockingTaskRunner::CapturePostTasks blocked;
+    BlockingTaskRunner::CapturePostTasks blocked(
+        blocking_main_thread_task_runner());
 
     CompletionEvent completion;
     Proxy::ImplThreadTaskRunner()->PostTask(
@@ -860,7 +861,8 @@ void ThreadProxy::BeginMainFrame(
     // This CapturePostTasks should be destroyed before CommitComplete() is
     // called since that goes out to the embedder, and we want the embedder
     // to receive its callbacks before that.
-    BlockingTaskRunner::CapturePostTasks blocked;
+    BlockingTaskRunner::CapturePostTasks blocked(
+        blocking_main_thread_task_runner());
 
     CompletionEvent completion;
     Proxy::ImplThreadTaskRunner()->PostTask(