Begin uniting the TabPersistentStore and StorageDelegate

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersister.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersister.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersister.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersister.java
new file mode 100644
index 0000000000000000000000000000000000000000..2a6bbe5df8c9e8d6388287a7bb0e33d82c9b492a
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabPersister.java
@@ -0,0 +1,78 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.tabmodel;
+
+import android.util.Log;
+
+import org.chromium.chrome.browser.TabState;
+import org.chromium.chrome.browser.util.StreamUtil;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * Interacts with the file system to persist Tab and TabModel data.
+ * TODO(dfalcantara): Flesh this out by moving common subclass functions into it.
+ */
+public abstract class TabPersister {
+    private static final String TAG = "TabPersister";
+
+    /** @return File representing the directory that is used to store Tab state information. */
+    protected abstract File getStateDirectory();
+
+    /**
+     * Returns a file pointing at the TabState corresponding to the given Tab.
+     * @param tabId ID of the TabState to locate.
+     * @param encrypted Whether or not the tab is encrypted.
+     * @return File pointing at the TabState for the Tab.
+     */
+    protected File getTabStateFile(int tabId, boolean encrypted) {
+        return TabState.getTabStateFile(getStateDirectory(), tabId, encrypted);
+    }
+
+    /**
+     * Saves the TabState with the given ID.
+     * @param tabId ID of the Tab.
+     * @param encrypted Whether or not the TabState is encrypted.
+     * @param state TabState for the Tab.
+     */
+    public boolean saveTabState(int tabId, boolean encrypted, TabState state) {
+        if (state == null) return false;
+
+        FileOutputStream stream = null;
+        try {
+            stream = new FileOutputStream(getTabStateFile(tabId, encrypted));
+            TabState.saveState(stream, state, encrypted);
+            return true;
+        } catch (FileNotFoundException exception) {
+            Log.w(TAG, "FileNotFoundException while attempt to TabState.");
+        } catch (IOException exception) {
+            Log.w(TAG, "IO Exception while attempting to save tab state.");
+        } catch (OutOfMemoryError e) {
+            Log.w(TAG, "Out of memory error while attempting to save tab state.  Erasing.");
+            deleteTabState(tabId, encrypted);
+        } finally {
+            StreamUtil.closeQuietly(stream);
+        }
+
+        return false;
+    }
+
+    /**
+     * Deletes the TabState corresponding to the given Tab.
+     * @param id ID of the TabState to delete.
+     * @param encrypted Whether or not the tab is encrypted.
+     */
+    public void deleteTabState(int id, boolean encrypted) {
+        TabState.deleteTabState(getStateDirectory(), id, encrypted);
+    }
+
+    protected FileOutputStream openTabStateOutputStream(int id, boolean encrypted)
+            throws IOException {
+        return new FileOutputStream(getTabStateFile(id, encrypted));
+    }
+}