Revert 202821 "Protect WebURLLoaderImpl::Context while receiving..."

> Protect WebURLLoaderImpl::Context while receiving responses.
> 
> A client's didReceiveResponse can cancel a request; by protecting the
> Context we avoid a use after free in this case.
> 
> Interestingly, we really had very good warning about this problem, see 
> https://codereview.chromium.org/11900002/ back in January.
> 
> R=darin
> BUG=241139
> 
> Review URL: https://chromiumcodereview.appspot.com/15738007

TBR=gavinp@chromium.org

Review URL: https://codereview.chromium.org/15859009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@202835 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/webkit_browsertest.cc

@@ -76,19 +76,4 @@ IN_PROC_BROWSER_TEST_F(WebKitBrowserTest, PrerenderNoCrash) {
   EXPECT_FALSE(shell()->web_contents()->IsCrashed());
 }
 
-// This is a browser test because DumpRenderTree doesn't run nested message
-// loops. The failure case was that a nested message triggered from an element
-// that has signalled an error but had an open request would receive a body for
-// the request and crash/fail an assertion.
-const char kErrorBodyNoCrash[] =
-    "files/error-body-no-crash.html";
-IN_PROC_BROWSER_TEST_F(WebKitBrowserTest, ErrorBodyNoCrash) {
-  ASSERT_TRUE(test_server()->Start());
-  GURL url = test_server()->GetURL(kErrorBodyNoCrash);
-
-  NavigateToURL(shell(), url);
-
-  EXPECT_FALSE(shell()->web_contents()->IsCrashed());
-}
-
 }  // namespace content

content/test/data/error-body-no-crash.html

-<!-- The showModalDialog call will force a nested message loop, which will
-     receive the 404 body and crash. -->
-<script src="page404.html"></script>
-<script>
-window.showModalDialog("javascript:window.close();");
-</script>

webkit/glue/weburlloader_impl.cc

@@ -637,7 +637,6 @@ void WebURLLoaderImpl::Context::OnReceivedResponse(
     }
   }
 
-  scoped_refptr<Context> protect(this);
   client_->didReceiveResponse(loader_, response);
 
   // We may have been cancelled after didReceiveResponse, which would leave us