Fix DCHECK, memory leak, and refactor PasswordStore to use CancelableRequest

content/browser/cancelable_request.cc

Index: content/browser/cancelable_request.cc
diff --git a/content/browser/cancelable_request.cc b/content/browser/cancelable_request.cc
index f1826fd023539a2ac46cd695d1e1709019df875b..5b369030f2f16848f11c41033fa5cc899383b955 100644
--- a/content/browser/cancelable_request.cc
+++ b/content/browser/cancelable_request.cc
@@ -4,7 +4,13 @@
 
 #include "content/browser/cancelable_request.h"
 
-CancelableRequestProvider::CancelableRequestProvider() : next_handle_(1) {
+const CancelableRequestProvider::Handle
+    CancelableRequestProvider::kInvalidHandle = 0;
+const CancelableRequestProvider::Handle
+    CancelableRequestProvider::kFirstHandle = 1;
+
+CancelableRequestProvider::CancelableRequestProvider()
+    : next_handle_(CancelableRequestProvider::kFirstHandle) {
 }
 
 CancelableRequestProvider::~CancelableRequestProvider() {
@@ -28,6 +34,7 @@ CancelableRequestProvider::Handle CancelableRequestProvider::AddRequest(
     handle = next_handle_;
     pending_requests_[next_handle_] = request;
     ++next_handle_;
+    DCHECK_NE(kInvalidHandle, next_handle_);
   }
 
   consumer->OnRequestAdded(this, handle);
@@ -41,6 +48,14 @@ void CancelableRequestProvider::CancelRequest(Handle handle) {
   CancelRequestLocked(pending_requests_.find(handle));
 }
 
+CancelableRequestProvider::Handle CancelableRequestProvider::InvalidHandle() {
+  return kInvalidHandle;
+}
+
+bool CancelableRequestProvider::HandleIsValid(Handle handle) {
+  return handle != kInvalidHandle;
+}
+
 void CancelableRequestProvider::CancelRequestLocked(
     const CancelableRequestMap::iterator& item) {
   pending_request_lock_.AssertAcquired();