[CustomTabs] Report the navigation start as absolute time

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

Index: chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
index 0b235af88a79661c00e1e37ae0e860939c802d01..c33886060342debc75215f4a5fd4ab24bbee9674 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
@@ -19,6 +19,7 @@ import android.os.Build;
 import android.os.Bundle;
 import android.os.Process;
 import android.os.StrictMode;
+import android.os.SystemClock;
 import android.support.customtabs.CustomTabsCallback;
 import android.support.customtabs.CustomTabsIntent;
 import android.support.customtabs.CustomTabsService;
@@ -30,6 +31,7 @@ import org.chromium.base.CommandLine;
 import org.chromium.base.Log;
 import org.chromium.base.SysUtils;
 import org.chromium.base.ThreadUtils;
+import org.chromium.base.TimeUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.base.library_loader.ProcessInitException;
@@ -41,6 +43,7 @@ import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.WarmupManager;
 import org.chromium.chrome.browser.device.DeviceClassManager;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
+import org.chromium.chrome.browser.metrics.PageLoadMetrics;
 import org.chromium.chrome.browser.net.spdyproxy.DataReductionProxySettings;
 import org.chromium.chrome.browser.preferences.PrefServiceBridge;
 import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
@@ -667,12 +670,21 @@ public class CustomTabsConnection {
      *
      * @param session Session identifier.
      * @param metricName Name of the page load metric.
+     * @param navigationStartTick Absolute navigation start time, as TimeTicks.
      * @param offsetMs Offset in ms from navigationStart.
      */
-    boolean notifyPageLoadMetric(CustomTabsSessionToken session, String metricName, long offsetMs) {
+    boolean notifyPageLoadMetric(CustomTabsSessionToken session, String metricName,
+            long navigationStartTick, long offsetMs) {
         CustomTabsCallback callback = mClientManager.getCallbackForSession(session);
         if (callback == null) return false;
+
+        // Convert navigationstart from time ticks to uptimeMillis.
+        long nativeNowUs = TimeUtils.nativeGetTimeTicksNowUs();
+        long javaNowUs = SystemClock.uptimeMillis() * 1000;
+        long offsetTick = nativeNowUs - javaNowUs;
+
         Bundle args = new Bundle();
+        args.putLong(PageLoadMetrics.NAVIGATION_START, (navigationStartTick - offsetTick) / 1000);
         args.putLong(metricName, offsetMs);
         try {
             callback.extraCallback(PAGE_LOAD_METRICS_CALLBACK, args);