[AW] Add INFO logs about important seed fetching events

This adds logging on debug builds of android for the following events:
 * Requesting a new seed from the service
 * Scheduling a new download job within the service
 * Downloading a new seed
 * Copying a seed to an app's data directory
 * Loading a seed and its age

I believe this will be enough information to verify that the system is
behaving as expected and to narrow down where the problem is if things
aren't working.

Test: Manually verify the logs are being printed.
Bug: 1042895
Change-Id: I1f6ec28c2cdc970db419bcc9b73ee0375221f2b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2006109
Commit-Queue: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Changwan Ryu <changwan@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733055}

android_webview/java/src/org/chromium/android_webview/VariationsSeedLoader.java

@@ -356,6 +356,7 @@ public class VariationsSeedLoader {
             return;
         }
 
+        VariationsUtils.debugLog("Requesting new seed from IVariationsSeedServer");
         SeedServerConnection connection = new SeedServerConnection(newSeedFd, oldSeedDate);
         connection.start();
     }
@@ -374,6 +375,8 @@ public class VariationsSeedLoader {
         if (seed != null) {
             AwVariationsSeedBridge.setSeed(seed);
             AwVariationsSeedBridge.setLoadedSeedFresh(isLoadedSeedFresh());
+            long seedAge = TimeUnit.MILLISECONDS.toSeconds(new Date().getTime() - seed.date);
+            VariationsUtils.debugLog("Loaded seed with age " + seedAge + "s");
         }
     }
 }

android_webview/java/src/org/chromium/android_webview/common/variations/VariationsUtils.java

@@ -10,6 +10,7 @@ import com.google.protobuf.ByteString;
 import com.google.protobuf.InvalidProtocolBufferException;
 
 import org.chromium.android_webview.proto.AwVariationsSeedOuterClass.AwVariationsSeed;
+import org.chromium.base.BuildInfo;
 import org.chromium.base.Log;
 import org.chromium.base.PathUtils;
 import org.chromium.components.variations.firstrun.VariationsSeedFetcher.SeedInfo;
@@ -155,4 +156,11 @@ public class VariationsUtils {
             closeSafely(out);
         }
     }
+
+    // Logs an INFO message if running in a debug build of Android.
+    public static void debugLog(String message) {
+        if (BuildInfo.isDebugAndroid()) {
+            Log.i(TAG, message);
+        }
+    }
 }

android_webview/nonembedded/java/src/org/chromium/android_webview/services/AwVariationsSeedFetcher.java

@@ -87,6 +87,7 @@ public class AwVariationsSeedFetcher extends JobService {
 
         // Check if it's already scheduled.
         if (getPendingJob(scheduler, JOB_ID) != null) {
+            VariationsUtils.debugLog("Seed download job already scheduled");
             return;
         }
 
@@ -95,10 +96,12 @@ public class AwVariationsSeedFetcher extends JobService {
         if (lastRequestTime != 0) {
             long now = (new Date()).getTime();
             if (now < lastRequestTime + MIN_JOB_PERIOD_MILLIS) {
+                VariationsUtils.debugLog("Throttling seed download job");
                 return;
             }
         }
 
+        VariationsUtils.debugLog("Scheduling seed download job");
         ComponentName thisComponent = new ComponentName(
                 ContextUtils.getApplicationContext(), AwVariationsSeedFetcher.class);
         JobInfo job = new JobInfo.Builder(JOB_ID, thisComponent)
@@ -125,6 +128,7 @@ public class AwVariationsSeedFetcher extends JobService {
             try {
                 VariationsUtils.updateStampTime();
 
+                VariationsUtils.debugLog("Downloading new seed");
                 VariationsSeedFetcher downloader =
                         sMockDownloader != null ? sMockDownloader : VariationsSeedFetcher.get();
                 String milestone = String.valueOf(VersionConstants.PRODUCT_MAJOR_VERSION);

android_webview/nonembedded/java/src/org/chromium/android_webview/services/VariationsSeedHolder.java

@@ -81,6 +81,7 @@ public class VariationsSeedHolder {
                 if (VariationsSeedHolder.this.mSeed == null) return;
 
                 if (mDestinationDate < VariationsSeedHolder.this.mSeed.date) {
+                    VariationsUtils.debugLog("Writing new seed to app's data directory");
                     writeSeedWithoutClosing(VariationsSeedHolder.this.mSeed, mDestination);
                 }
             } finally {