Introduce the plumbing necessary to report Unrecoverable error from model safe workers.

chrome/browser/sync/glue/browser_thread_model_worker.cc

Index: chrome/browser/sync/glue/browser_thread_model_worker.cc
diff --git a/chrome/browser/sync/glue/browser_thread_model_worker.cc b/chrome/browser/sync/glue/browser_thread_model_worker.cc
index de2ae424550d4b2ea3d7ad3edbb274d0e1c201ba..9c1abdf6e9239f8bea97d278d10200cbf2d92b4b 100644
--- a/chrome/browser/sync/glue/browser_thread_model_worker.cc
+++ b/chrome/browser/sync/glue/browser_thread_model_worker.cc
@@ -17,11 +17,12 @@ BrowserThreadModelWorker::BrowserThreadModelWorker(
 
 BrowserThreadModelWorker::~BrowserThreadModelWorker() {}
 
-void BrowserThreadModelWorker::DoWorkAndWaitUntilDone(Callback0::Type* work) {
+UnrecoverableErrorInfo BrowserThreadModelWorker::DoWorkAndWaitUntilDone(
+    const WorkCallback& work) {
+  UnrecoverableErrorInfo error_info;
   if (BrowserThread::CurrentlyOn(thread_)) {
     DLOG(WARNING) << "Already on thread " << thread_;
-    work->Run();
-    return;
+    return work.Run();
   }
   WaitableEvent done(false, false);
   if (!BrowserThread::PostTask(
@@ -31,17 +32,21 @@ void BrowserThreadModelWorker::DoWorkAndWaitUntilDone(Callback0::Type* work) {
           this,
           &BrowserThreadModelWorker::CallDoWorkAndSignalTask,
           work,
-          &done))) {
+          &done,
+          &error_info))) {
     NOTREACHED() << "Failed to post task to thread " << thread_;
-    return;
+    return error_info;
   }
   done.Wait();
+  return error_info;
 }
 
 void BrowserThreadModelWorker::CallDoWorkAndSignalTask(
-    Callback0::Type* work, WaitableEvent* done) {
+    const WorkCallback& work,
+    WaitableEvent* done,
+    UnrecoverableErrorInfo* error_info) {
   DCHECK(BrowserThread::CurrentlyOn(thread_));
-  work->Run();
+  *error_info = work.Run();
   done->Signal();
 }
 
@@ -55,8 +60,10 @@ DatabaseModelWorker::DatabaseModelWorker()
 DatabaseModelWorker::~DatabaseModelWorker() {}
 
 void DatabaseModelWorker::CallDoWorkAndSignalTask(
-    Callback0::Type* work, WaitableEvent* done) {
-  BrowserThreadModelWorker::CallDoWorkAndSignalTask(work, done);
+    const WorkCallback& work,
+    WaitableEvent* done,
+    UnrecoverableErrorInfo* error_info) {
+  BrowserThreadModelWorker::CallDoWorkAndSignalTask(work, done, error_info);
 }
 
 FileModelWorker::FileModelWorker()
@@ -65,8 +72,10 @@ FileModelWorker::FileModelWorker()
 FileModelWorker::~FileModelWorker() {}
 
 void FileModelWorker::CallDoWorkAndSignalTask(
-    Callback0::Type* work, WaitableEvent* done) {
-  BrowserThreadModelWorker::CallDoWorkAndSignalTask(work, done);
+    const WorkCallback& work,
+    WaitableEvent* done,
+    UnrecoverableErrorInfo* error_info) {
+  BrowserThreadModelWorker::CallDoWorkAndSignalTask(work, done, error_info);
 }
 
 }  // namespace browser_sync