Disk cache: Protect the code against misuse...

So avoid crashing even if the destructor is not
called before killing the IO thread.

BUG=49271
TEST=none


Review URL: http://codereview.chromium.org/3044006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52924 0039d316-1c4b-4281-b951-d872f2087c98

net/disk_cache/in_flight_backend_io.h

@@ -5,6 +5,7 @@
 #ifndef NET_DISK_CACHE_IN_FLIGHT_BACKEND_IO_H_
 #define NET_DISK_CACHE_IN_FLIGHT_BACKEND_IO_H_
 
+#include <list>
 #include <string>
 
 #include "base/message_loop_proxy.h"

net/disk_cache/in_flight_io.cc

@@ -37,7 +37,7 @@ void InFlightIO::WaitForPendingIO() {
 // Runs on a background thread.
 void InFlightIO::OnIOComplete(BackgroundIO* operation) {
 #ifndef NDEBUG
-  if (callback_thread_ == MessageLoop::current()) {
+  if (callback_thread_->BelongsToCurrentThread()) {
     DCHECK(single_thread_ || !running_);
     single_thread_ = true;
   }
@@ -66,7 +66,7 @@ void InFlightIO::InvokeCallback(BackgroundIO* operation, bool cancel_task) {
 
 // Runs on the primary thread.
 void InFlightIO::OnOperationPosted(BackgroundIO* operation) {
-  DCHECK(callback_thread_ == MessageLoop::current());
+  DCHECK(callback_thread_->BelongsToCurrentThread());
   io_list_.insert(operation);
 }
 

net/disk_cache/in_flight_io.h

@@ -7,7 +7,7 @@
 
 #include <set>
 
-#include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
 #include "base/waitable_event.h"
 
 namespace disk_cache {
@@ -89,8 +89,8 @@ class BackgroundIO : public base::RefCountedThreadSafe<BackgroundIO> {
 class InFlightIO {
  public:
   InFlightIO()
-      : callback_thread_(MessageLoop::current()), running_(false),
-        single_thread_(false) {}
+      : callback_thread_(base::MessageLoopProxy::CreateForCurrentThread()),
+        running_(false), single_thread_(false) {}
   virtual ~InFlightIO() {}
 
   // Blocks the current thread until all IO operations tracked by this object
@@ -121,7 +121,7 @@ class InFlightIO {
   typedef std::set<scoped_refptr<BackgroundIO> > IOList;
 
   IOList io_list_;  // List of pending, in-flight io operations.
-  MessageLoop* callback_thread_;
+  scoped_refptr<base::MessageLoopProxy> callback_thread_;
 
   bool running_;  // True after the first posted operation completes.
   bool single_thread_;  // True if we only have one thread.