[Android History] Add clear browsing data button and privacy disclaimers

chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java
index 43f99ff2c541938a78ff254bca69a6ba6dfce696..3dbf0792818a471fa835499163e517c0d202a2bf 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadHistoryAdapter.java
@@ -340,6 +340,7 @@ public class DownloadHistoryAdapter extends DateDividedAdapter implements Downlo
         mRegularDownloadItems.filter(mFilter, mFilteredItems);
         mIncognitoDownloadItems.filter(mFilter, mFilteredItems);
         mOfflinePageItems.filter(mFilter, mFilteredItems);
+        clear(false);

[gone, 2016/12/12 19:14:13]

Feels like this should still be called by #loadItems() directly to avoid
situations where another set of items is loaded before it's been cleared. 
Should be asserted in some way that doesn't conflict with HistoryAdapter, at
least.

[Theresa, 2016/12/12 20:09:03]

As discussed offline, I updated the JavaDoc for #loadItems to change the promise
about whether data is cleared since History shouldn't clear items before loading
more.

         loadItems(mFilteredItems);
     }