Refactor Pickle Read methods to use higher performance PickleIterator.

There was a lot of redundant error checking and initialization code in all Pickle Read methods because of the void** iterator type. This change replaces the void* iterator with PickleIterator, which encapsulates the read pointer so that less error checking and initialization code is needed for reading.

PickleIterator has all the necessary data to do the actual reading. The advantage of having it provide Read methods (as opposed to leaving them solely in the Pickle interface) is that the callers do not need to pass around the const Pickle* once they have a PickleIterator.

Followup CLs will refactor the call sites to remove const Pickle* arguments where they are now unnecessary. Then the Pickle::Read* methods can be removed entirely.

The alternative approach would have been to change the Pickle::Read methods to non-const and remove the iterator parameter (making Read methods advance an internal read pointer). Unfortunately, the const Read with iterator design is entrenched throughout the chromium code, making this a much more complex change with the same performance outcome.

BUG=13108

Review URL: https://chromiumcodereview.appspot.com/9447084

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@125447 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 1 insertions, 1 deletions

diff --git a/net/http/http_response_headers_unittest.cc b/net/http/http_response_headers_unittest.cc
index 775946c..f7c5e6f5 100644
--- a/net/http/http_response_headers_unittest.cc
+++ b/net/http/http_response_headers_unittest.cc
@@ -475,7 +475,7 @@ TEST(HttpResponseHeadersTest, Persist) {
     Pickle pickle;
     parsed1->Persist(&pickle, tests[i].options);
 
-    void* iter = NULL;
+    PickleIterator iter(pickle);
     scoped_refptr<net::HttpResponseHeaders> parsed2(
         new net::HttpResponseHeaders(pickle, &iter));