[Offline] Adding archiver interface

BUG=491352

Review URL: https://codereview.chromium.org/1174803002

Cr-Commit-Position: refs/heads/master@{#334608}

5 files changed, 161 insertions, 7 deletions

diff --git a/components/offline_pages/BUILD.gn b/components/offline_pages/BUILD.gn
index e4de8cc..36cee85 100644
--- a/components/offline_pages/BUILD.gn
+++ b/components/offline_pages/BUILD.gn
@@ -5,6 +5,7 @@
 # GYP: //components/offline_pages.gypi:offline_pages
 static_library("offline_pages") {
   sources = [
+    "offline_page_archiver.h",
     "offline_page_item.cc",
     "offline_page_item.h",
     "offline_page_metadata_store.cc",
diff --git a/components/offline_pages/offline_page_archiver.h b/components/offline_pages/offline_page_archiver.h
new file mode 100644
index 0000000..8cc0566
--- /dev/null
+++ b/components/offline_pages/offline_page_archiver.h
@@ -0,0 +1,90 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ARCHIVER_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ARCHIVER_H_
+
+#include "base/files/file_path.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+// Interface of a class responsible for creation of the archive for offline use.
+//
+// Archiver will be implemented by embedder and may have additional methods that
+// are not interesting from the perspective of OfflinePageModel. Example of such
+// extra information or capability is a way to enumerate available WebContents
+// to find the one that needs to be used to create archive (or to map it to the
+// URL passed in CreateArchive in some other way).
+//
+// Archiver will be responsible for naming the file that is being saved (it has
+// URL, title and the whole page content at its disposal). For that it should be
+// also configured with the path where the archives are stored.
+//
+// Archiver should be able to archive multiple pages in parallel, as these are
+// asynchronous calls carried out by some other component.
+//
+// If archiver gets two consecutive requests to archive the same page (may be
+// run in parallel) it can generate 2 different names for files and save the
+// same page separately, as if these were 2 completely unrelated pages. It is up
+// to the caller (e.g. OfflinePageModel) to make sure that situation like that
+// does not happen.
+//
+// If the page is not completely loaded, it is up to the implementation of the
+// archiver whether to respond with ERROR_CONTENT_UNAVAILBLE, wait longer to
+// actually snapshot a complete page, or snapshot whatever is available at that
+// point in time (what the user sees).
+//
+// TODO(fgorski): Add ability to delete archive.
+// TODO(fgorski): Add ability to check that archive exists.
+// TODO(fgorski): Add ability to refresh an existing archive in one step.
+// TODO(fgorski): Add ability to identify all of the archives in the directory,
+// to enable to model to reconcile the archives.
+class OfflinePageArchiver {
+ public:
+  // Represents an in progress request to archive a page.
+  class Request {
+   public:
+    virtual ~Request() {}
+
+    // Cancels an in progress request to archive a page.
+    virtual void Cancel() = 0;
+    virtual const GURL& url() const = 0;
+  };
+
+  // Errors that will be reported when archive creation fails.
+  enum ArchiverResult {
+    SUCCESSFULLY_CREATED,       // Archive created successfully.
+    ERROR_UNKNOWN,              // Don't know what went wrong.
+    ERROR_DEVICE_FULL,          // Cannot save the archive - device is full.
+    ERROR_CANCELLED,            // Caller cancelled the request.
+    ERROR_CONTENT_UNAVAILABLE,  // Content to archive is not available.
+  };
+
+  // Interface of the clients that requests to archive pages.
+  class Client {
+   public:
+    virtual ~Client() {}
+
+    // Callback called by the archiver when archiver creation is complete.
+    // |result| will indicate SUCCESSFULLY_CREATED upon success, or a specific
+    // error, when it failed.
+    virtual void OnCreateArchiveDone(Request* request,
+                                     ArchiverResult result,
+                                     const base::FilePath& file_path) = 0;
+  };
+
+  virtual ~OfflinePageArchiver() {}
+
+  // Starts creating the archive. Will pass result by calling methods on the
+  // passed in client. Caller owns the returned request object.
+  // If request is deleted during the archiving, the callback will not be
+  // invoked. The archive might however be created.
+  virtual scoped_ptr<Request> CreateArchive(const GURL& url,
+                                            Client* client) = 0;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_ARCHIVER_H_
diff --git a/components/offline_pages/offline_page_model.cc b/components/offline_pages/offline_page_model.cc
index 5fd54d0..f357d7e3 100644
--- a/components/offline_pages/offline_page_model.cc
+++ b/components/offline_pages/offline_page_model.cc
@@ -11,18 +11,29 @@
 
 namespace offline_pages {
 
-OfflinePageModel::OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store)
-    : store_(store.Pass()) {
+OfflinePageModel::OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store,
+                                   OfflinePageArchiver* archiver)
+    : store_(store.Pass()),
+      archiver_(archiver) {
+  DCHECK(archiver);
 }
 
 OfflinePageModel::~OfflinePageModel() {
 }
 
 void OfflinePageModel::Shutdown() {
-  NOTIMPLEMENTED();
 }
 
 void OfflinePageModel::SavePageOffline(const GURL& url) {
+}
+
+void OfflinePageModel::OnCreateArchiveDone(
+    OfflinePageArchiver::Request* request,
+    OfflinePageArchiver::ArchiverResult result,
+    const base::FilePath& file_path) {
+  // TODO(fgorski): Match request against one of the expected requests
+  // TODO(fgorski): Create an entry in the offline pages metadata store for that
+  //                request.
   NOTIMPLEMENTED();
 }
 
diff --git a/components/offline_pages/offline_page_model.h b/components/offline_pages/offline_page_model.h
index d32ace1..44eaf37 100644
--- a/components/offline_pages/offline_page_model.h
+++ b/components/offline_pages/offline_page_model.h
@@ -10,6 +10,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
+#include "components/offline_pages/offline_page_archiver.h"
 
 class GURL;
 
@@ -20,14 +21,21 @@ class OfflinePageMetadataStore;
 
 // Serivce for saving pages offline, storing the offline copy and metadata, and
 // retrieving them upon request.
-class OfflinePageModel : public KeyedService {
+class OfflinePageModel : public KeyedService,
+                         public OfflinePageArchiver::Client {
  public:
-  explicit OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store);
+  OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store,
+                   OfflinePageArchiver* archiver);
   ~OfflinePageModel() override;
 
-  // KeyedService:
+  // KeyedService implementation.
   void Shutdown() override;
 
+  // OfflinePageArchiver::Client implementation.
+  void OnCreateArchiveDone(OfflinePageArchiver::Request* request,
+                           OfflinePageArchiver::ArchiverResult error,
+                           const base::FilePath& file_path) override;
+
   // Saves the page loaded in the web contents offline.
   void SavePageOffline(const GURL& url);
 
@@ -41,6 +49,9 @@ class OfflinePageModel : public KeyedService {
   // Persistent store for offline page metadata.
   scoped_ptr<OfflinePageMetadataStore> store_;
 
+  // Offline page archiver. Outlives the model. Owned by the embedder.
+  OfflinePageArchiver* archiver_;
+
   DISALLOW_COPY_AND_ASSIGN(OfflinePageModel);
 };
 
diff --git a/components/offline_pages/offline_page_model_unittest.cc b/components/offline_pages/offline_page_model_unittest.cc
index b6119ef..d153190 100644
--- a/components/offline_pages/offline_page_model_unittest.cc
+++ b/components/offline_pages/offline_page_model_unittest.cc
@@ -38,12 +38,53 @@ void OfflinePageTestStore::RemoveOfflinePage(const GURL& page_url,
                                              const UpdateCallback& callback) {
 }
 
+class OfflinePageTestArchiverRequest : public OfflinePageArchiver::Request {
+ public:
+  explicit OfflinePageTestArchiverRequest(const  GURL& url) : url_(url) {}
+  ~OfflinePageTestArchiverRequest() override {}
+
+  void Cancel() override;
+  const GURL& url() const override { return url_; }
+
+ private:
+  GURL url_;
+};
+
+void OfflinePageTestArchiverRequest::Cancel() {
+}
+
+
+class OfflinePageTestArchiver : public OfflinePageArchiver {
+ public:
+  ~OfflinePageTestArchiver() override;
+
+  // OfflinePageArchiver implementation:
+  scoped_ptr<Request> CreateArchive(const GURL& url,
+                                    Client* client) override;
+};
+
+OfflinePageTestArchiver::~OfflinePageTestArchiver() {
+}
+
+scoped_ptr<OfflinePageArchiver::Request> OfflinePageTestArchiver::CreateArchive(
+    const GURL& url,
+    Client* client) {
+  scoped_ptr<OfflinePageTestArchiverRequest> request(
+      new OfflinePageTestArchiverRequest(url));
+  return request.Pass();
+}
+
 class OfflinePageModelTest : public testing::Test {
  public:
   OfflinePageModelTest();
   ~OfflinePageModelTest() override;
 
   scoped_ptr<OfflinePageMetadataStore> BuildStore();
+
+  OfflinePageTestArchiver* archiver() { return &archiver_; }
+
+ private:
+  OfflinePageTestArchiver archiver_;
 };
 
 OfflinePageModelTest::OfflinePageModelTest() {
@@ -59,7 +100,7 @@ scoped_ptr<OfflinePageMetadataStore> OfflinePageModelTest::BuildStore() {
 TEST_F(OfflinePageModelTest, Initialize) {
   scoped_ptr<OfflinePageMetadataStore> store = BuildStore();
   OfflinePageMetadataStore* store_ptr = store.get();
-  OfflinePageModel model(store.Pass());
+  OfflinePageModel model(store.Pass(), archiver());
   EXPECT_EQ(store_ptr, model.GetStoreForTesting());
 }