Log the size of each of the stores and complete DB on launch and after each

components/safe_browsing_db/v4_protocol_manager_util.h

Index: components/safe_browsing_db/v4_protocol_manager_util.h
diff --git a/components/safe_browsing_db/v4_protocol_manager_util.h b/components/safe_browsing_db/v4_protocol_manager_util.h
index 403a56ff4b01c400bd723e5ab656b2cbe9045fb3..ab9987c7de8773614d2a233f85b448a25464676c 100644
--- a/components/safe_browsing_db/v4_protocol_manager_util.h
+++ b/components/safe_browsing_db/v4_protocol_manager_util.h
@@ -193,6 +193,8 @@ enum V4OperationResult {
 };
 
 // A class that provides static methods related to the Pver4 protocol.
+// TODO(vakh): Consider making this class a namespace instead.
+// TODO(vakh): Re-order the methods in alphabetical order.
 class V4ProtocolManagerUtil {
  public:
   // Canonicalizes url as per Google Safe Browsing Specification.
@@ -264,6 +266,9 @@ class V4ProtocolManagerUtil {
   static void SetClientInfoFromConfig(ClientInfo* client_info,
                                       const V4ProtocolConfig& config);
 
+  // Returns the size of the file at |file_path|, or 0 if there's an error.
+  static int64_t GetFileSizeOrZero(const base::FilePath& file_path);
+
  private:
   V4ProtocolManagerUtil(){};
   FRIEND_TEST_ALL_PREFIXES(V4ProtocolManagerUtilTest, TestBackOffLogic);