Add instrumentation to track down a crash....

chrome/browser/net/url_fetcher.cc

Index: chrome/browser/net/url_fetcher.cc
===================================================================
--- chrome/browser/net/url_fetcher.cc	(revision 31506)
+++ chrome/browser/net/url_fetcher.cc	(working copy)
@@ -95,6 +95,11 @@
   // specified by the protection manager, we'll give up.
   int num_retries_;
 
+  // Temporary member variable to test whether requests are being started
+  // after they have already been cancelled.
+  // TODO(eroman): Remove this after done investigating 27074.
+  bool was_cancelled_;

[wtc, 2009/11/10 01:09:25]

You explained what this member is for, but you should also
describe what it is.
  True if the request has been cancelled.
or
  True if CancelURLRequest has been called.

+
   friend class URLFetcher;
   DISALLOW_COPY_AND_ASSIGN(Core);
 };
@@ -135,12 +140,13 @@
       buffer_(new net::IOBuffer(kBufferSize)),
       protect_entry_(URLFetcherProtectManager::GetInstance()->Register(
           original_url_.host())),
-      num_retries_(0) {
+      num_retries_(0),
+      was_cancelled_(false) {
 }
 
 void URLFetcher::Core::Start() {
   DCHECK(delegate_loop_);
-  DCHECK(request_context_getter_) << "We need an URLRequestContext!";
+  CHECK(request_context_getter_) << "We need an URLRequestContext!";
   ChromeThread::PostDelayedTask(
       ChromeThread::IO, FROM_HERE,
       NewRunnableMethod(this, &Core::StartURLRequest),
@@ -199,7 +205,9 @@
 
 void URLFetcher::Core::StartURLRequest() {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  DCHECK(!request_);
+  CHECK(!was_cancelled_);
+  CHECK(request_context_getter_);
+  CHECK(!request_);
 
   request_ = new URLRequest(original_url_, this);
   int flags = request_->load_flags() | load_flags_;
@@ -252,6 +260,7 @@
   // delete the object, but we cannot delay the destruction of the request
   // context.
   request_context_getter_ = NULL;
+  was_cancelled_ = true;
 }
 
 void URLFetcher::Core::OnCompletedURLRequest(const URLRequestStatus& status) {