[Payments] Fix debug build check failure

Refer here for details:
https://cs.chromium.org/chromium/src/base/bind_internal.h?rcl=9050148b1dffa4d6e695d0732c368e954e15a4e0&l=787

Change-Id: I6aab905a1fc8d21967a0aff5df6fea3eab7decfc
Reviewed-on: https://chromium-review.googlesource.com/1208726
Commit-Queue: Ganggui Tang <gogerald@chromium.org>
Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589180}

content/browser/payments/payment_app_installer.cc

@@ -46,6 +46,8 @@ class SelfDeleteInstaller
   void Init(WebContents* web_contents, bool use_cache) {
     DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+    AddRef();  // Balanced by Release() in FinishInstallation.
+
     // TODO(crbug.com/782270): Listen for web contents events to terminate
     // installation early.
     Observe(web_contents);
@@ -188,6 +190,7 @@ class SelfDeleteInstaller
     }
 
     Observe(nullptr);
+    Release();  // Balanced by AddRef() in the constructor.
   }
 
   std::string app_name_;