Implemented ExternalData interface on DownloadItem and used it for SafeBrowsing.

content/browser/download/download_item_impl.cc

Index: content/browser/download/download_item_impl.cc
diff --git a/content/browser/download/download_item_impl.cc b/content/browser/download/download_item_impl.cc
index 73c3cc9435fd6f40dbc4e7f224812936908a697d..3109e93e1ed6e2f9c525c1703772b66061df1254 100644
--- a/content/browser/download/download_item_impl.cc
+++ b/content/browser/download/download_item_impl.cc
@@ -14,6 +14,7 @@
 #include "base/i18n/string_search.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/stl_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "content/browser/download/download_create_info.h"
@@ -260,6 +261,8 @@ DownloadItemImpl::~DownloadItemImpl() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   TransitionTo(REMOVING);
+  STLDeleteContainerPairSecondPointers(
+      external_data_map_.begin(), external_data_map_.end());
   delegate_->AssertStateConsistent(this);
   delegate_->Detach();
 }
@@ -761,6 +764,26 @@ void DownloadItemImpl::OffThreadCancel(DownloadFileManager* file_manager) {
                  file_manager, download_id_));
 }
 
+DownloadItem::ExternalData*

[asanka, 2011/12/07 04:10:57]

Style nit: The method implementation order isn't the same as the order in the
header.

[Randy Smith (Not in Mondays), 2011/12/07 18:36:12]

Done.

+DownloadItemImpl::GetExternalData(const void* key) {
+  if (external_data_map_.count(key) == 0)

[asanka, 2011/12/07 04:10:57]

Just curious; why not ContainsKey()?

[Randy Smith (Not in Mondays), 2011/12/07 18:36:12]

Prejudice on my part, which it's probably time for me to get over in the name of
drinking the Chrome Koolaid (I haven't seen the point of using a separate
routine that pretty much does the same thing as an available one liner, though
to be fair, the routine is probably better performing).  Changed.

+    return NULL;
+  return external_data_map_[key];
+}
+
+void DownloadItemImpl::SetExternalData(
+    const void* key, DownloadItem::ExternalData* data) {
+  std::map<const void*, ExternalData*>::iterator it =
+      external_data_map_.find(key);
+
+  if (it == external_data_map_.end()) {
+    external_data_map_[key] = data;
+  } else if (it->second != data) {
+    delete it->second;
+    it->second = data;
+  }
+}
+
 void DownloadItemImpl::Init(bool active) {
   // TODO(rdsmith): Change to DCHECK after http://crbug.com/85408 resolved.
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));