Queue Precache.Fetch.FailureReasons values.

Queue the histogram values until native libs have been loaded, at which
point all the values in the queue will be removed and posted to UMA.
This is necessary to try to determine if the underreporting for this
metric is a result of PrecacheServiceLauncher's onReceive() not being
called that often, or of native libs not being available most of the
time.

BUG=499532

Review URL: https://codereview.chromium.org/1337253002

Cr-Commit-Position: refs/heads/master@{#348655}

1 files changed, 18 insertions, 4 deletions

diff --git a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheServiceLauncher.java b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheServiceLauncher.java
index 8d10397..989d3e5 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheServiceLauncher.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/precache/PrecacheServiceLauncher.java
@@ -23,7 +23,9 @@ import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.components.precache.DeviceState;
 
+import java.util.ArrayDeque;
 import java.util.EnumSet;
+import java.util.Queue;
 
 /**
  * BroadcastReceiver that determines when conditions are right for precaching, and starts the
@@ -53,6 +55,8 @@ public class PrecacheServiceLauncher extends BroadcastReceiver {
 
     private PrecacheLauncher mPrecacheLauncher = PrecacheLauncher.get();
 
+    private Queue<Integer> mFailureReasonsToRecord = new ArrayDeque<Integer>();
+
     @VisibleForTesting
     void setDeviceState(DeviceState deviceState) {
         mDeviceState = deviceState;
@@ -153,11 +157,21 @@ public class PrecacheServiceLauncher extends BroadcastReceiver {
      *
      * @param context The context passed to onReceive().
      */
-    private void recordFailureReasons(Context context) {
-        if (!LibraryLoader.isInitialized()) return;
-
+    @VisibleForTesting
+    void recordFailureReasons(Context context) {
         int reasons = FailureReason.bitValue(failureReasons(context));
-        RecordHistogram.recordSparseSlowlyHistogram("Precache.Fetch.FailureReasons", reasons);
+
+        // Queue up this failure reason, for the next time we are able to record it in UMA.
+        mFailureReasonsToRecord.add(reasons);
+
+        // If native libraries are loaded, then we are able to flush our queue to UMA.
+        if (LibraryLoader.isInitialized()) {
+            Integer reasonsToRecord;
+            while ((reasonsToRecord = mFailureReasonsToRecord.poll()) != null) {
+                RecordHistogram.recordSparseSlowlyHistogram(
+                        "Precache.Fetch.FailureReasons", reasonsToRecord);
+            }
+        }
     }
 
     @Override