content: Some code cleanup related to shared memory allocation.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 8616dbdfd1c22b389660eb92cf4314797a34a306..75942331342ae28c2495a61f1ad1690863424e2d 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1367,8 +1367,7 @@ void RenderThreadImpl::RecordComputedAction(const std::string& action) {
 
 std::unique_ptr<base::SharedMemory>
 RenderThreadImpl::HostAllocateSharedMemoryBuffer(size_t size) {
-  return ChildThreadImpl::AllocateSharedMemory(size, thread_safe_sender(),
-                                               nullptr);
+  return ChildThreadImpl::AllocateSharedMemory(size);
 }
 
 cc::SharedBitmapManager* RenderThreadImpl::GetSharedBitmapManager() {