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..1d52abaf82afa66b2623717e2e4afc0e94db55ca 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 +45,51 @@ PageAbortReason GetAbortReasonForEndReason(PageEndReason end_reason) {
 
 }  // namespace
 
+bool IsGoogleHostnameAndGetPrefix(const GURL& url,

[RyanSturm, 2017/05/15 20:42:06]

nit: Thoughts on getting rid of the out param and returning a
base::Optional<base::StringPiece>? Maybe rename it GetPrefixForGoogleHostName if
that makes sense.

[Bryan McQuade, 2017/05/16 03:59:15]

This is a great idea. I needed to change to optional<std::string> since we
sometimes return string offsets into a stack-allocated string piece, which blows
up. using std::string guarantees consistent storage that can live beyond
returning from a function.

+                                  base::StringPiece* out_google_host_prefix) {
+  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 false;
+
+  // 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") {
+    if (out_google_host_prefix)
+      *out_google_host_prefix = "";
+    return true;
+  }
+
+  if (!base::EndsWith(hostname_minus_registry, ".google",
+                      base::CompareCase::INSENSITIVE_ASCII)) {
+    return false;
+  }
+
+  if (out_google_host_prefix) {
+    *out_google_host_prefix = hostname_minus_registry.substr(
+        0, hostname_minus_registry.length() - strlen(".google"));
+  }
+  return true;
+}
+
+bool IsGoogleHostname(const GURL& url) {
+  return IsGoogleHostnameAndGetPrefix(url, nullptr);
+}
+
 bool WasStartedInForegroundOptionalEventInForeground(
     const base::Optional<base::TimeDelta>& event,
     const PageLoadExtraInfo& info) {