Various cleaups for AMP page load metrics.

chrome/browser/page_load_metrics/page_load_metrics_util.cc

Index: chrome/browser/page_load_metrics/page_load_metrics_util.cc
diff --git a/chrome/browser/page_load_metrics/page_load_metrics_util.cc b/chrome/browser/page_load_metrics/page_load_metrics_util.cc
index aba5131a409bdfe4a83b2bb5e1697e9ba252d748..22ec5505e23665708b80541e24c2f059047659b0 100644
--- a/chrome/browser/page_load_metrics/page_load_metrics_util.cc
+++ b/chrome/browser/page_load_metrics/page_load_metrics_util.cc
@@ -7,6 +7,8 @@
 #include <algorithm>
 
 #include "chrome/common/page_load_metrics/page_load_timing.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+#include "url/gurl.h"
 
 namespace page_load_metrics {
 
@@ -43,6 +45,45 @@ PageAbortReason GetAbortReasonForEndReason(PageEndReason end_reason) {
 
 }  // namespace
 
+base::Optional<std::string> GetGoogleHostnamePrefix(const GURL& url) {
+  const size_t registry_length =
+      net::registry_controlled_domains::GetRegistryLength(
+          url,
+
+          // Do not include unknown registries (registries that don't have any
+          // matches in effective TLD names).
+          net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES,
+
+          // Do not include private registries, such as appspot.com. We don't
+          // want to match URLs like www.google.appspot.com.
+          net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
+
+  const base::StringPiece hostname = url.host_piece();
+  if (registry_length == 0 || registry_length == std::string::npos ||
+      registry_length >= hostname.length()) {
+    return base::Optional<std::string>();
+  }
+
+  // Removes the tld and the preceding dot.
+  const base::StringPiece hostname_minus_registry =
+      hostname.substr(0, hostname.length() - (registry_length + 1));
+
+  if (hostname_minus_registry == "google")
+    return std::string("");
+
+  if (!base::EndsWith(hostname_minus_registry, ".google",
+                      base::CompareCase::INSENSITIVE_ASCII)) {
+    return base::Optional<std::string>();
+  }
+
+  return std::string(hostname_minus_registry.substr(
+      0, hostname_minus_registry.length() - strlen(".google")));
+}
+
+bool IsGoogleHostname(const GURL& url) {
+  return GetGoogleHostnamePrefix(url).has_value();
+}
+
 bool WasStartedInForegroundOptionalEventInForeground(
     const base::Optional<base::TimeDelta>& event,
     const PageLoadExtraInfo& info) {