Add browser test for AEC dump.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 17444b3cb4400017ab8f71dfecfd6c2e1399fe72..5a620ec97251d0ae6f02aad08c6a23a3d52f4625 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -214,6 +214,12 @@ IPC::PlatformFileForTransit CreateAecDumpFileForProcess(
   }
   return IPC::GetFileHandleForProcess(aec_dump_file, process, true);
 }
+
+// Does nothing. Just to avoid races between enable and disable.
+void DisableAecDumpOnFileThread() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+}
+
 #endif
 
 // the global list of all renderer processes
@@ -1516,7 +1522,11 @@ void RenderProcessHostImpl::EnableAecDump(const base::FilePath& file) {
 }
 
 void RenderProcessHostImpl::DisableAecDump() {
-  Send(new MediaStreamMsg_DisableAecDump());
+  BrowserThread::PostTaskAndReply(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&DisableAecDumpOnFileThread),

[phoglund_chromium, 2013/12/18 14:20:46]

So you queue something on the file thread just to make sure it has processed all
previous requests?

[Henrik Grunell, 2013/12/19 08:43:14]

Exactly. I don't know if there's another way that's common or better. This will
at least for sure avoid races, though it's kind of weird to just post back and
forth and do nothing on the file thread.

Added comment to clarify.

[phoglund_chromium, 2013/12/19 11:57:04]

I think it kind of makes sense. I can't think of a better way spontanously.

+      base::Bind(&RenderProcessHostImpl::SendDisableAecDumpToRenderer,
+                 weak_factory_.GetWeakPtr()));
 }
 #endif
 
@@ -1960,6 +1970,10 @@ void RenderProcessHostImpl::SendAecDumpFileToRenderer(
     return;
   Send(new MediaStreamMsg_EnableAecDump(file_for_transit));
 }
+
+void RenderProcessHostImpl::SendDisableAecDumpToRenderer() {
+  Send(new MediaStreamMsg_DisableAecDump());
+}
 #endif
 
 }  // namespace content