[Android WebView] Keep a reference to the exclusive data dir lock file.

android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java

Index: android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java b/android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
index 5bc5ed20db83fbd55e62eb8c2593276e57d6b097..9c5d8d6ff198b830457d65a59c69500bf56a32cc 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
@@ -35,6 +35,7 @@ public abstract class AwBrowserProcess {
 
     private static final String TAG = "AwBrowserProcess";
     private static final String EXCLUSIVE_LOCK_FILE = "webview_data.lock";
+    private static RandomAccessFile sLockFile;
     private static FileLock sExclusiveFileLock;
 
     /**
@@ -115,9 +116,9 @@ public abstract class AwBrowserProcess {
             File lockFile = new File(dataPath, EXCLUSIVE_LOCK_FILE);
             boolean success = false;
             try {
-                // Note that the file is not closed intentionally.
-                RandomAccessFile file = new RandomAccessFile(lockFile, "rw");
-                sExclusiveFileLock = file.getChannel().tryLock();
+                // Note that the file is kept open intentionally.
+                sLockFile = new RandomAccessFile(lockFile, "rw");
+                sExclusiveFileLock = sLockFile.getChannel().tryLock();
                 success = sExclusiveFileLock != null;
             } catch (IOException e) {
                 Log.w(TAG, "Failed to create lock file " + lockFile, e);