Add support for icons.{src,type,density} in Manifest.

content/renderer/manifest/manifest_manager.cc

Index: content/renderer/manifest/manifest_manager.cc
diff --git a/content/renderer/manifest/manifest_manager.cc b/content/renderer/manifest/manifest_manager.cc
index 88ef6ac499269e12dcf5018265b0cd6991b57126..08612b819c6c742c0990bd4d259b05f23888c348 100644
--- a/content/renderer/manifest/manifest_manager.cc
+++ b/content/renderer/manifest/manifest_manager.cc
@@ -59,6 +59,12 @@ void ManifestManager::OnRequestManifestComplete(
         ipc_manifest.short_name.string().substr(0,
                                                 Manifest::kMaxIPCStringLength),
         ipc_manifest.short_name.is_null());
+  for (size_t i = 0; i < ipc_manifest.icons.size(); ++i) {
+    ipc_manifest.icons[i].type = base::NullableString16(
+        ipc_manifest.icons[i].type.string().substr(
+            0, Manifest::kMaxIPCStringLength),
+        ipc_manifest.icons[i].type.is_null());
+  }
 
   Send(new ManifestManagerHostMsg_RequestManifestResponse(
       routing_id(), request_id, ipc_manifest));