Factor out NetworkID and caching mechanism from n_q_e.{h,cc}

net/nqe/cached_network_quality.cc

Index: net/nqe/cached_network_quality.cc
diff --git a/net/nqe/cached_network_quality.cc b/net/nqe/cached_network_quality.cc
index 5902f75a08da08b0a25e8f1701d111ba43e28a0b..d4e454da17d42683aa17b30d8fda299284a5a684 100644
--- a/net/nqe/cached_network_quality.cc
+++ b/net/nqe/cached_network_quality.cc
@@ -10,10 +10,12 @@ namespace nqe {
 
 namespace internal {
 
+CachedNetworkQuality::CachedNetworkQuality() {}
+
 CachedNetworkQuality::CachedNetworkQuality(
+    base::TimeTicks last_update_time,
     const NetworkQuality& network_quality)
-    : last_update_time_(base::TimeTicks::Now()),
-      network_quality_(network_quality) {}
+    : last_update_time_(last_update_time), network_quality_(network_quality) {}
 
 CachedNetworkQuality::CachedNetworkQuality(const CachedNetworkQuality& other)
     : last_update_time_(other.last_update_time_),
@@ -21,6 +23,13 @@ CachedNetworkQuality::CachedNetworkQuality(const CachedNetworkQuality& other)
 
 CachedNetworkQuality::~CachedNetworkQuality() {}
 
+CachedNetworkQuality& CachedNetworkQuality::operator=(
+    const CachedNetworkQuality& other) {
+  last_update_time_ = other.last_update_time_;
+  network_quality_ = other.network_quality_;
+  return *this;
+}
+
 bool CachedNetworkQuality::OlderThan(
     const CachedNetworkQuality& cached_network_quality) const {
   return last_update_time_ < cached_network_quality.last_update_time_;