Fix strict mode violation in TabPersistentStore.cleanupPersistentData()

base/android/java/src/org/chromium/base/PathUtils.java

Index: base/android/java/src/org/chromium/base/PathUtils.java
diff --git a/base/android/java/src/org/chromium/base/PathUtils.java b/base/android/java/src/org/chromium/base/PathUtils.java
index 09c3b082409a052df102c591c3d69709969f1345..991ec25aa87cd9408a706619dc808dcc4a9d3c83 100644
--- a/base/android/java/src/org/chromium/base/PathUtils.java
+++ b/base/android/java/src/org/chromium/base/PathUtils.java
@@ -10,6 +10,7 @@ import android.os.AsyncTask;
 import android.os.Environment;
 import android.os.StrictMode;
 import android.os.SystemClock;
+import android.support.annotation.WorkerThread;
 
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.MainDex;
@@ -33,6 +34,7 @@ public abstract class PathUtils {
     private static AsyncTask<String, Void, String[]> sDirPathFetchTask;
 
     private static File sThumbnailDirectory;
+    private static Object sLazyInitLock = new Object();

[gone, 2016/02/18 17:45:35]

private static final?  Can't imagine ever recreating the lock.

[agrieve, 2016/02/23 21:28:38]

Deleted in favour of using sDirPathFetchTask

 
     // Prevent instantiation.
     private PathUtils() {}
@@ -103,18 +105,18 @@ public abstract class PathUtils {
         return getDirectoryPath(CACHE_DIRECTORY);
     }
 
+    @WorkerThread
     public static File getThumbnailCacheDirectory(Context appContext) {
+        ThreadUtils.assertOnFileThread();
         if (sThumbnailDirectory == null) {
-            // Temporarily allowing disk access while fixing. TODO: http://crbug.com/473356
-            StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
-            StrictMode.allowThreadDiskWrites();
-            try {
-                long time = SystemClock.elapsedRealtime();
-                sThumbnailDirectory = appContext.getDir(THUMBNAIL_DIRECTORY, Context.MODE_PRIVATE);
-                RecordHistogram.recordTimesHistogram("Android.StrictMode.ThumbnailCacheDir",
-                        SystemClock.elapsedRealtime() - time, TimeUnit.MILLISECONDS);
-            } finally {
-                StrictMode.setThreadPolicy(oldPolicy);
+            synchronized (sLazyInitLock) {
+                if (sThumbnailDirectory == null) {
+                    long time = SystemClock.elapsedRealtime();
+                    sThumbnailDirectory =
+                            appContext.getDir(THUMBNAIL_DIRECTORY, Context.MODE_PRIVATE);
+                    RecordHistogram.recordTimesHistogram("Android.StrictMode.ThumbnailCacheDir",
+                            SystemClock.elapsedRealtime() - time, TimeUnit.MILLISECONDS);
+                }
             }
         }
         return sThumbnailDirectory;