Fix for possible crashes due to pointer value being null

content/renderer/render_frame_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_frame_impl.h"
 
 #include <map>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 209 matching lines @@
 
 const size_t kExtraCharsBeforeAndAfterSelection = 100;
 
 typedef std::map<int, RenderFrameImpl*> RoutingIDFrameMap;
 static base::LazyInstance<RoutingIDFrameMap> g_routing_id_frame_map =
     LAZY_INSTANCE_INITIALIZER;
 
 typedef std::map<blink::WebFrame*, RenderFrameImpl*> FrameMap;
 base::LazyInstance<FrameMap> g_frame_map = LAZY_INSTANCE_INITIALIZER;
 
-int64 ExtractPostId(const WebHistoryItem& item) {
-  if (item.isNull())
+int64 ExtractPostId(HistoryEntry* entry) {
+  if (!entry)
     return -1;
 
-  if (item.httpBody().isNull())
+  const WebHistoryItem& item = entry->root();
+  if (item.isNull() || item.httpBody().isNull())
     return -1;
 
   return item.httpBody().identifier();
 }
 
 WebURLResponseExtraDataImpl* GetExtraDataFromResponse(
     const WebURLResponse& response) {
   return static_cast<WebURLResponseExtraDataImpl*>(response.extraData());
 }
 
@@ skipping 3522 matching lines @@
       params.transition = ui::PageTransitionFromInt(
           params.transition | ui::PAGE_TRANSITION_CLIENT_REDIRECT);
     } else {
       params.referrer = RenderViewImpl::GetReferrerFromRequest(
           frame, ds->request());
     }
 
     base::string16 method = request.httpMethod();
     if (EqualsASCII(method, "POST")) {
       params.is_post = true;
-      params.post_id = ExtractPostId(entry->root());
+      params.post_id = ExtractPostId(entry);
     }
 
     // Send the user agent override back.
     params.is_overriding_user_agent = internal_data->is_overriding_user_agent();
 
     // Track the URL of the original request.  We use the first entry of the
     // redirect chain if it exists because the chain may have started in another
     // process.
     params.original_request_url = GetOriginalRequestURL(ds);
 
@@ skipping 651 matching lines @@
 
 #if defined(ENABLE_BROWSER_CDMS)
 RendererCdmManager* RenderFrameImpl::GetCdmManager() {
   if (!cdm_manager_)
     cdm_manager_ = new RendererCdmManager(this);
   return cdm_manager_;
 }
 #endif  // defined(ENABLE_BROWSER_CDMS)
 
 }  // namespace content