[FileEncap9] Extract ResearchLogDirectory class

Previously used a monotonically increasing int.  Now uses uuid and nanoseconds.

squashed in:
    [FileEncap11] Read preference from ResearchSettings
    Change-Id: Ic779e0a69db6b16e92c6f4b63dbe7b7add566ab6

    [FileEncap12] Simplify directory cleanup invocation
    Change-Id: I688047409c0343d32b11447fb625dfb726c731ec

    [FileEncap14] Change log filename syntax
    Change-Id: I9243b20b2eb392f81ab8c5c3d19315211240e0bc

Change-Id: I5c9d70e0cb7b0965158e17dd71dfab796bd9a440

1 files changed, 11 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/research/ResearchSettings.java b/java/src/com/android/inputmethod/research/ResearchSettings.java
index 11e9ac77a..c0bc03fde 100644
--- a/java/src/com/android/inputmethod/research/ResearchSettings.java
+++ b/java/src/com/android/inputmethod/research/ResearchSettings.java
@@ -26,6 +26,8 @@ public final class ResearchSettings {
             "pref_research_logger_enabled_flag";
     public static final String PREF_RESEARCH_LOGGER_HAS_SEEN_SPLASH =
             "pref_research_logger_has_seen_splash";
+    public static final String PREF_RESEARCH_LAST_DIR_CLEANUP_TIME =
+            "pref_research_last_dir_cleanup_time";
 
     private ResearchSettings() {
         // Intentional empty constructor for singleton.
@@ -58,4 +60,13 @@ public final class ResearchSettings {
             final boolean hasSeenSplash) {
         prefs.edit().putBoolean(PREF_RESEARCH_LOGGER_HAS_SEEN_SPLASH, hasSeenSplash).apply();
     }
+
+    public static long readResearchLastDirCleanupTime(final SharedPreferences prefs) {
+        return prefs.getLong(PREF_RESEARCH_LAST_DIR_CLEANUP_TIME, 0L);
+    }
+
+    public static void writeResearchLastDirCleanupTime(final SharedPreferences prefs,
+            final long lastDirCleanupTime) {
+        prefs.edit().putLong(PREF_RESEARCH_LAST_DIR_CLEANUP_TIME, lastDirCleanupTime).apply();
+    }
 }