Re-land: cc: Implement shared worker contexts.

content/child/child_process.cc

Index: content/child/child_process.cc
diff --git a/content/child/child_process.cc b/content/child/child_process.cc
index 01675b321f75522a487e83c714780307f89c228e..ec7ecd11f77e63f8a2aec722282c7add39f9c08f 100644
--- a/content/child/child_process.cc
+++ b/content/child/child_process.cc
@@ -54,19 +54,18 @@ ChildProcess::ChildProcess()
 ChildProcess::~ChildProcess() {
   DCHECK(g_lazy_tls.Pointer()->Get() == this);
 
+  // Kill the main thread object before nulling child_process, since
+  // destruction code might depend on it.
+  if (main_thread_)  // null in unittests.
+    main_thread_->Shutdown();

[piman, 2015/09/14 21:54:38]

I think you still want to do this after shutdown_event_.Signal(), which is there
to avoid deadlocks (e.g. some thread sending a sync message via a
SyncMessageFilter, and the main thread waiting for that thread to finish).

[reveman, 2015/09/15 20:38:35]

Done. But that meant allowing ChildThreadImpl::AllocateSharedMemory to fail
without a NOTREACHED during shutdown.

+
   // Signal this event before destroying the child process.  That way all
   // background threads can cleanup.
   // For example, in the renderer the RenderThread instances will be able to
   // notice shutdown before the render process begins waiting for them to exit.
   shutdown_event_.Signal();
 
-  // Kill the main thread object before nulling child_process, since
-  // destruction code might depend on it.
-  if (main_thread_) {  // null in unittests.
-    main_thread_->Shutdown();
-    main_thread_.reset();
-  }
-
+  main_thread_.reset();
   g_lazy_tls.Pointer()->Set(NULL);
   io_thread_.Stop();
 }