Add Precache.CacheStatus.Prefetch UMA.

components/precache/core/precache_database_unittest.cc

Index: components/precache/core/precache_database_unittest.cc
diff --git a/components/precache/core/precache_database_unittest.cc b/components/precache/core/precache_database_unittest.cc
index 5098786c7193461bcd97f20c63b5c43f72a495e4..98564d38b23b57862266fc0bc2b7617ce536fe64 100644
--- a/components/precache/core/precache_database_unittest.cc
+++ b/components/precache/core/precache_database_unittest.cc
@@ -260,6 +260,7 @@ TEST_F(PrecacheDatabaseTest, PrecacheOverNetwork) {
 
   ExpectNewSample("Precache.DownloadedPrecacheMotivated", kSize);
   ExpectNewSample("Precache.Latency.Prefetch", kLatency.InMilliseconds());
+  ExpectNewSample("Precache.CacheStatus.Prefetch", kFromNetwork);
   ExpectNewSample("Precache.Freshness.Prefetch", kFreshnessBucket10K);
   ExpectNoOtherSamples();
 }
@@ -273,6 +274,8 @@ TEST_F(PrecacheDatabaseTest, PrecacheFromCacheWithURLTableEntry) {
   EXPECT_EQ(BuildURLTableMap(kURL, kFetchTime), GetActualURLTableMap());
 
   ExpectNewSample("Precache.Latency.Prefetch", 0);
+  ExpectNewSample("Precache.CacheStatus.Prefetch",
+                  net::HttpResponseInfo::ENTRY_USED);
   ExpectNewSample("Precache.Freshness.Prefetch", kFreshnessBucket10K);
   ExpectNoOtherSamples();
 }
@@ -283,6 +286,8 @@ TEST_F(PrecacheDatabaseTest, PrecacheFromCacheWithoutURLTableEntry) {
   EXPECT_TRUE(GetActualURLTableMap().empty());
 
   ExpectNewSample("Precache.Latency.Prefetch", 0);
+  ExpectNewSample("Precache.CacheStatus.Prefetch",
+                  net::HttpResponseInfo::ENTRY_USED);
   ExpectNewSample("Precache.Freshness.Prefetch", kFreshnessBucket10K);
   ExpectNoOtherSamples();
 }