Support for png images served with "image/x-png" mime type

net/base/mime_util.cc

Index: net/base/mime_util.cc
diff --git a/net/base/mime_util.cc b/net/base/mime_util.cc
index fdb16fd8f7ef0b0f22b2d2e232198587ce19344d..b488c9e3f98fc67bfdc74d44215af383ffcfb6cf 100644
--- a/net/base/mime_util.cc
+++ b/net/base/mime_util.cc
@@ -158,6 +158,7 @@ static const MimeInfo secondary_mappings[] = {
   { "image/tiff", "tiff,tif" },
   { "image/x-xbitmap", "xbm" },
   { "image/svg+xml", "svg,svgz" },
+  { "image/x-png", "png"},
   { "message/rfc822", "eml" },
   { "text/plain", "txt,text" },
   { "text/html", "ehtml" },
@@ -260,7 +261,8 @@ static const char* const supported_image_types[] = {
   "image/bmp",
   "image/vnd.microsoft.icon",    // ico
   "image/x-icon",    // ico
-  "image/x-xbitmap"  // xbm
+  "image/x-xbitmap",  // xbm
+  "image/x-png"
 };
 
 // A list of media types: http://en.wikipedia.org/wiki/Internet_media_type