[Offline Pages] Add cached offline page utils and show usage in settings.

chrome/browser/android/offline_pages/offline_page_utils.h

Index: chrome/browser/android/offline_pages/offline_page_utils.h
diff --git a/chrome/browser/android/offline_pages/offline_page_utils.h b/chrome/browser/android/offline_pages/offline_page_utils.h
index f539f9369b54e00dd91a3ac3b010ecc440dcc744..956e939ceea6fc91339337eed6ffeee97a680228 100644
--- a/chrome/browser/android/offline_pages/offline_page_utils.h
+++ b/chrome/browser/android/offline_pages/offline_page_utils.h
@@ -9,8 +9,13 @@
 
 #include "base/callback.h"
 #include "components/offline_pages/core/offline_page_model.h"
+#include "components/offline_pages/core/offline_page_types.h"
 #include "url/gurl.h"
 
+namespace base {
+class Time;
+}
+
 namespace content {
 class BrowserContext;
 class WebContents;
@@ -114,6 +119,16 @@ class OfflinePageUtils {
   // of download resource.
   static bool CanDownloadAsOfflinePage(const GURL& url,
                                        const std::string& contents_mime_type);
+
+  // Get total size of cache offline pages for a given time range. Returns false
+  // when an OfflinePageModel cannot be acquired using the |browser_context|, or
+  // the time range is invalid (|begin_time| > |end_time|). Also returning false
+  // means no callback should be expected.
+  static bool GetCachedOfflinePageSizeBetween(
+      content::BrowserContext* browser_context,
+      const SizeInBytesCallback& callback,
+      const base::Time& begin_time,
+      const base::Time& end_time);
 };
 
 }  // namespace offline_pages