Cast StatFs return values to long

On devices with large storage partitions, we could overflow when
converting free blocks to free bytes. Cast to long to avoid this.

Bug: 3327970
Change-Id: I3c007fc5c9fc758a03ee6ec0b7ee5a1423c170b3
diff --git a/src/com/android/browser/WebStorageSizeManager.java b/src/com/android/browser/WebStorageSizeManager.java
index 5f76f72..bd7f8e6 100644
--- a/src/com/android/browser/WebStorageSizeManager.java
+++ b/src/com/android/browser/WebStorageSizeManager.java
@@ -141,11 +141,11 @@
         }
 
         public long getFreeSpaceSizeBytes() {
-            return mFs.getAvailableBlocks() * mFs.getBlockSize();
+            return (long)(mFs.getAvailableBlocks()) * mFs.getBlockSize();
         }
 
         public long getTotalSizeBytes() {
-            return mFs.getBlockCount() * mFs.getBlockSize();
+            return (long)(mFs.getBlockCount()) * mFs.getBlockSize();
         }
     };