Makes the OfflinePageBridge.getAllPages method asynchronous.

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
index b18caa136cff5e19d374757724b8521a1933c83a..265c517796b77c6081e1a8d2db059dd1d2233672 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
@@ -55,7 +55,7 @@ public class OfflinePageBridge {
     private static Integer sFeatureMode;
 
     /**
-     * Callback used to saving an offline page.
+     * Callback used when saving an offline page.
      */
     public interface SavePageCallback {
         /**
@@ -71,7 +71,7 @@ public class OfflinePageBridge {
     }
 
     /**
-     * Callback used to deleting an offline page.
+     * Callback used when deleting an offline page.
      */
     public interface DeletePageCallback {
         /**
@@ -86,9 +86,21 @@ public class OfflinePageBridge {
     }
 
     /**
+     * Callback that delivers information about multiple offline page entries.
+     */
+    public interface MultipleOfflinePageItemCallback {
+        public void onGetItems(List<OfflinePageItem> allOfflinePages);

[fgorski, 2016/03/28 17:58:46]

nit: do you need public keyword?
nit: add documentation. (Will the list be empty or null when delivered?)

[dewittj, 2016/03/31 18:43:17]

Done.

+    }
+
+    /**
+     * Callback used when determining whether we have any offline pages.
+     */
+    public interface HasPagesCallback { void onHasPagesDone(boolean hasPages); }
+
+    /**
      * Base observer class listeners to be notified of changes to the offline page model.
      */
-    public abstract static class OfflinePageModelObserver {
+    public static class OfflinePageModelObserver {

[fgorski, 2016/03/28 17:58:46]

why are you removing abstract?

[dewittj, 2016/03/31 18:43:18]

Done.

         /**
          * Called when the native side of offline pages is loaded and now in usable state.
          */
@@ -109,7 +121,7 @@ public class OfflinePageBridge {
         public void offlinePageDeleted(long offlineId, ClientId clientId) {}
     }
 
-    private static long getTotalSize(List<OfflinePageItem> offlinePages) {
+    static long getTotalSize(List<OfflinePageItem> offlinePages) {

[fgorski, 2016/03/28 17:58:46]

I think you can remove this method, as it is no longer used here.
It was probably missed by my or some other patch.

[dewittj, 2016/03/31 18:43:17]

Done.

         long totalSize = 0;
         for (OfflinePageItem offlinePage : offlinePages) {
             totalSize += offlinePage.getFileSize();
@@ -225,9 +237,40 @@ public class OfflinePageBridge {
     }
 
     /**
-     * @return Gets all available offline pages. Requires that the model is already loaded.
+     * Gets all available offline pages, returning results via the provided callback. Requires that
+     * the model is already loaded.

[fgorski, 2016/03/28 17:58:46]

add assert if that is required.

[dewittj, 2016/03/31 18:43:17]

Done.

+     *
+     * @param callback The callback to run when the operation completes.
      */
-    public List<OfflinePageItem> getAllPages() {
+    public void getAllPages(final MultipleOfflinePageItemCallback callback) {
+        OfflinePageModelObserver observer = new OfflinePageModelObserver() {
+            @Override
+            public void offlinePageModelLoaded() {
+                callback.onGetItems(getAllPagesInternal());
+                removeObserver(this);
+            }
+        };
+
+        if (mIsNativeOfflinePageModelLoaded) {
+            observer.offlinePageModelLoaded();
+            return;
+        }
+        addObserver(observer);
+    }
+
+    public void hasPages(final HasPagesCallback callback) {
+        getAllPages(new MultipleOfflinePageItemCallback() {
+            @Override
+            public void onGetItems(List<OfflinePageItem> allPages) {

[fgorski, 2016/03/28 17:58:46]

at least put a TODO that this has to be quickly fixed to not make a full read.

[dewittj, 2016/03/31 18:43:17]

Done.

+                callback.onHasPagesDone(!allPages.isEmpty());
+            }
+        });
+    }
+
+    /**
+     * @return All available offline pages. Requires that the model is already loaded.
+     */
+    private List<OfflinePageItem> getAllPagesInternal() {
         assert mIsNativeOfflinePageModelLoaded;
         List<OfflinePageItem> result = new ArrayList<OfflinePageItem>();
         nativeGetAllPages(mNativeOfflinePageBridge, result);
@@ -344,19 +387,10 @@ public class OfflinePageBridge {
      */
     public void deletePage(final ClientId clientId, DeletePageCallback callback) {
         assert mIsNativeOfflinePageModelLoaded;
+        ArrayList<ClientId> ids = new ArrayList<ClientId>();
+        ids.add(clientId);
 
-        recordFreeSpaceHistograms("OfflinePages.DeletePage.FreeSpacePercentage",
-                "OfflinePages.DeletePage.FreeSpaceMB");
-
-        DeletePageCallback callbackWrapper = wrapCallbackWithHistogramReporting(callback);
-        Set<Long> ids = getOfflineIdsForClientId(clientId);
-        if (ids.size() == 0) {
-            callback.onDeletePageDone(DeletePageResult.NOT_FOUND);
-            return;
-        }
-        for (Long offlineId : ids) {
-            nativeDeletePage(mNativeOfflinePageBridge, callbackWrapper, offlineId);
-        }
+        deletePagesByClientId(ids, callback);
     }
 
     /**
@@ -375,8 +409,8 @@ public class OfflinePageBridge {
         deletePages(idList, callback);
     }
 
-    protected void deletePages(List<Long> offlineIds, DeletePageCallback callback) {
-        long[] ids = new long[offlineIds.size()];
+    protected void deletePages(List<Long> offlineIds, final DeletePageCallback callback) {

[fgorski, 2016/03/28 17:58:46]

do you need final here? and next line?

[dewittj, 2016/03/31 18:43:17]

Done.

+        final long[] ids = new long[offlineIds.size()];
         for (int i = 0; i < offlineIds.size(); i++) {
             ids[i] = offlineIds.get(i);
         }
@@ -506,6 +540,8 @@ public class OfflinePageBridge {
 
         mIsNativeOfflinePageModelLoaded = false;
         mNativeOfflinePageBridge = 0;
+
+        mObservers.clear();

[fgorski, 2016/03/28 17:58:46]

we should probably add a TODO: create a model destroyed method on the observer
and send it out here.

[dewittj, 2016/03/31 18:43:17]

Done.

     }
 
     @CalledByNative
@@ -553,8 +589,6 @@ public class OfflinePageBridge {
     private native void nativeSavePage(long nativeOfflinePageBridge, SavePageCallback callback,
             WebContents webContents, String clientNamespace, String clientId);
     private native void nativeMarkPageAccessed(long nativeOfflinePageBridge, long offlineId);
-    private native void nativeDeletePage(
-            long nativeOfflinePageBridge, DeletePageCallback callback, long offlineId);
     private native void nativeDeletePages(
             long nativeOfflinePageBridge, DeletePageCallback callback, long[] offlineIds);
     private native void nativeGetPagesToCleanUp(