Use FakeServer-based invalidations for Sync tests

sync/test/fake_server/fake_server_http_post_provider.cc

Index: sync/test/fake_server/fake_server_http_post_provider.cc
diff --git a/sync/test/fake_server/fake_server_http_post_provider.cc b/sync/test/fake_server/fake_server_http_post_provider.cc
index e0b34368fa349a1241a3ab0b228ed2634b889119..9d2285a57d1ee05dc7a7ac1af461595fb64e3383 100644
--- a/sync/test/fake_server/fake_server_http_post_provider.cc
+++ b/sync/test/fake_server/fake_server_http_post_provider.cc
@@ -6,8 +6,11 @@
 
 #include <string>
 
+#include "base/synchronization/waitable_event.h"
+#include "content/public/browser/browser_thread.h"
 #include "sync/test/fake_server/fake_server.h"
 
+using content::BrowserThread;
 using syncer::HttpPostProviderInterface;
 
 namespace fake_server {
@@ -32,7 +35,8 @@ void FakeServerHttpPostProviderFactory::Destroy(
 }
 
 FakeServerHttpPostProvider::FakeServerHttpPostProvider(
-    FakeServer* fake_server) : fake_server_(fake_server) { }
+    FakeServer* fake_server) : fake_server_(fake_server),
+                               post_complete_(false, false) { }
 
 FakeServerHttpPostProvider::~FakeServerHttpPostProvider() { }
 
@@ -54,13 +58,28 @@ void FakeServerHttpPostProvider::SetPostPayload(const char* content_type,
   request_content_.assign(content, content_length);
 }
 
+void FakeServerHttpPostProvider::OnPostComplete() {
+  post_complete_.Signal();
+}
+
 bool FakeServerHttpPostProvider::MakeSynchronousPost(int* error_code,
                                                      int* response_code) {
-  // This assumes that a POST is being made to /command.
-  *error_code = fake_server_->HandleCommand(request_content_,
-                                            response_code,
-                                            &response_);
-  return (*error_code == 0);
+  // It is assumed that a POST is being made to /command.
+  base::Closure callback = base::Bind(
+      &FakeServerHttpPostProvider::OnPostComplete, base::Unretained(this));
+  BrowserThread::PostTask(BrowserThread::UI,

[rlarocque, 2014/04/22 18:22:22]

If this code is to live in sync/test, then I'm not sure if it's allowed to know
about the UI thread.  It should be OK to pass in a thread or
scoped_refptr<SequencedTaskRunner> that it could use, though.

[pval...(no longer on Chromium), 2014/04/24 01:08:53]

Done.

+                          FROM_HERE,
+                          base::Bind(&FakeServer::HandleCommand,
+                                     base::Unretained(fake_server_),
+                                     base::ConstRef(request_content_),
+                                     base::ConstRef(callback),
+                                     error_code,
+                                     response_code,
+                                     &response_));
+  const int kTimeoutSecs = 5;
+  bool signaled = post_complete_.TimedWait(
+      base::TimeDelta::FromSeconds(kTimeoutSecs));
+  return signaled && *error_code == 0;
 }
 
 int FakeServerHttpPostProvider::GetResponseContentLength() const {