WebView: Adding Fast Variations Seed SafeMode action Seed Age Logging

In order to enable verification that the Fast Variations Seed SafeMode
action has successfully received a SafeMode variations seed instead
of the normal Variations seed, a log statement is added exclusively for
the SafeMode action when it executes.

(cherry picked from commit 7553023)

Test: Visual inspection of the logs via logcat on test devices
Bug: 1395513
Change-Id: Ib0abd2c576a1855ef5e84c83275ed7fccaad273d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4568131
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Commit-Queue: Adam Walls <avvall@google.com>
Cr-Original-Commit-Position: refs/heads/main@{#1152217}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4593924
Cr-Commit-Position: refs/branch-heads/5790@{#410}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

android_webview/java/src/org/chromium/android_webview/variations/FastVariationsSeedSafeModeAction.java

@@ -28,6 +28,8 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.Date;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
 
 /**
  * A {@link SafeModeAction} to ensure the variations seed is distributed on an app's first run.
@@ -75,8 +77,12 @@ public boolean execute() {
         sHasRun = true;
         long currDateTime = new Date().getTime();
         SeedParser parser = new SeedParser();
-
         long stampTime = sSeedFile.lastModified();
+        long ageInMillis = currDateTime - stampTime;
+
+        if (sSeedFile.exists() && ageInMillis > 0) {
+            logSeedFileAge(ageInMillis);
+        }
         // If we see that the local seed file has not exceeded the
         // maximum seed age of 15 minutes, parse the local seed instead
         // of requesting a new one from the ContentProvider
@@ -95,6 +101,16 @@ public boolean execute() {
         }
     }
 
+    private void logSeedFileAge(long ageInMillis) {
+        int seconds = (int) (ageInMillis / 1000) % 60;
+        int minutes = (int) (ageInMillis / TimeUnit.MINUTES.toMillis(1)) % 60;
+        int hrs = (int) (ageInMillis / TimeUnit.HOURS.toMillis(1));
+
+        String formattedAge =
+                String.format(Locale.US, "%02d:%02d:%02d (hh:mm:ss)", hrs, minutes, seconds);
+        Log.i(TAG, "Seed file age - " + formattedAge);
+    }
+
     /**
      * This class queries {@link SafeModeVariationsSeedContentProvider} for the
      * latest variations seed.
@@ -211,6 +227,7 @@ private boolean writeToSeedFile() {
             String filePath = sSeedFile.getPath();
             try (FileOutputStream out = new FileOutputStream(filePath, false)) {
                 out.write(mProtoAsByteArray);
+                out.flush();
                 return true;
             } catch (IOException e) {
                 Log.e(TAG, "Failed writing seed file: " + e.getMessage());