PlzNavigate: fix crash when updating redirect timing.

third_party/WebKit/Source/web/WebDataSourceImpl.cpp

Index: third_party/WebKit/Source/web/WebDataSourceImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebDataSourceImpl.cpp b/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
index 1772d017f5f785f0f157a9a55a58e61930579d6d..21ff72fc163dfa940fe0225b69ca7ad9334b696a 100644
--- a/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
+++ b/third_party/WebKit/Source/web/WebDataSourceImpl.cpp
@@ -77,10 +77,12 @@ void WebDataSourceImpl::appendRedirect(const WebURL& url)
 
 void WebDataSourceImpl::updateNavigation(double redirectStartTime, double redirectEndTime, double fetchStartTime, const WebVector<WebURL>& redirectChain)
 {
-    for (size_t i = 0; i + 1 < redirectChain.size(); ++i)
-        didRedirect(redirectChain[i], redirectChain[i + 1]);
-    timing().setRedirectStart(redirectStartTime);
-    timing().setRedirectEnd(redirectEndTime);
+    if (redirectChain.size() >= 2) {

[Nate Chapin, 2016/09/30 23:03:57]

Please add a comment to explain the significance of 2 here.

+        for (size_t i = 0; i + 1 < redirectChain.size(); ++i)
+            didRedirect(redirectChain[i], redirectChain[i + 1]);
+        timing().setRedirectStart(redirectStartTime);
+        timing().setRedirectEnd(redirectEndTime);
+    }
     timing().setFetchStart(fetchStartTime);
 }