Enable LeakTracker on release builds.

This is intended to be temporary, so we can get data from the dev channel on why URLRequest objects are leaking at shutdown.

WARNING: it may cause a slight slowdown on page cycler.

Also as part of this change, I switched the order that we check URLFetcher / URLRequest.
This is simply so that if both URLFetcher and URLRequest have leaked, we will report the URLFetcher leak rather than the URLRequest leak.

BUG=http://crbug.com/21199, http://crbug.com/18372

Review URL: http://codereview.chromium.org/217005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@26765 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 20 insertions, 3 deletions

diff --git a/base/leak_tracker.h b/base/leak_tracker.h
index de6ff29..9084f9a 100644
--- a/base/leak_tracker.h
+++ b/base/leak_tracker.h
@@ -5,8 +5,16 @@
 #ifndef BASE_LEAK_TRACKER_H_
 #define BASE_LEAK_TRACKER_H_
 
-// Only enable leak tracking in debug builds.
-#ifndef NDEBUG
+// Temporarily enable LeakTracker in all builds (both
+// release and debug). This will have an impact on performance, but
+// is intended to help track down a leak which reproduces on dev
+// channel.
+//
+// TODO(eroman): Restore the old code which only enabled LeakTracker
+// for debug builds.
+//
+// http://crbug.com/21199, http://crbug.com/18372
+#ifndef ENABLE_LEAK_TRACKER
 #define ENABLE_LEAK_TRACKER
 #endif
 
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index 68a3dc3..f971e80 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -106,8 +106,17 @@ class IOThread : public BrowserProcessSubThread {
  protected:
   virtual void CleanUp() {
     // URLFetcher and URLRequest instances must NOT outlive the IO thread.
-    base::LeakTracker<URLRequest>::CheckForLeaks();
+    //
+    // Strictly speaking, URLFetcher's CheckForLeaks() should be done on the
+    // UI thread. However, since there _shouldn't_ be any instances left
+    // at this point, it shouldn't be a race.
+    //
+    // We check URLFetcher first, since if it has leaked then an associated
+    // URLRequest will also have leaked. However it is more useful to
+    // crash showing the callstack of URLFetcher's allocation than its
+    // URLRequest member.
     base::LeakTracker<URLFetcher>::CheckForLeaks();
+    base::LeakTracker<URLRequest>::CheckForLeaks();
 
     BrowserProcessSubThread::CleanUp();
   }