Added a CRWBrowsingDataStoreDelegate

This delegate is consulted whenever a CRWBrowsingDataStore's mode wants to
become |ACTIVE| or |INACTIVE|.

The default behavior of stashing and restoring browsing data does not fit all
use cases and this decision needs to be delegated over.

Added a TODO to actually consult the delegate when a mode change occurs.

BUG=480654

Review URL: https://codereview.chromium.org/1151063004

Cr-Commit-Position: refs/heads/master@{#332293}

4 files changed, 81 insertions, 0 deletions

diff --git a/ios/web/crw_browsing_data_store.mm b/ios/web/crw_browsing_data_store.mm
index 646bb5a..4f36a22 100644
--- a/ios/web/crw_browsing_data_store.mm
+++ b/ios/web/crw_browsing_data_store.mm
@@ -84,6 +84,8 @@ enum OperationType {
 
 @implementation CRWBrowsingDataStore {
   web::BrowserState* _browserState;  // Weak, owns this object.
+  // The delegate.
+  base::WeakNSProtocol<id<CRWBrowsingDataStoreDelegate>> _delegate;
   // The mode of the CRWBrowsingDataStore.
   CRWBrowsingDataStoreMode _mode;
   // The dictionary that maps a browsing data type to its
@@ -180,6 +182,14 @@ enum OperationType {
   return result;
 }
 
+- (id<CRWBrowsingDataStoreDelegate>)delegate {
+  return _delegate;
+}
+
+- (void)setDelegate:(id<CRWBrowsingDataStoreDelegate>)delegate {
+  _delegate.reset(delegate);
+}
+
 + (BOOL)automaticallyNotifiesObserversForKey:(NSString*)key {
   // It is necessary to override this for |mode| because the default KVO
   // behavior in NSObject is to fire a notification irrespective of if an actual
@@ -241,6 +251,9 @@ enum OperationType {
         (void (^)(BOOL success))completionHandler {
   DCHECK([NSThread isMainThread]);
 
+  // TODO(shreyasv): Consult the delegate here if it wants to |DELETE| instead.
+  // crbug.com/480654.
+
   base::WeakNSObject<CRWBrowsingDataStore> weakSelf(self);
   [self performOperationWithType:RESTORE
             browsingDataManagers:[self allBrowsingDataManagers]
@@ -254,6 +267,9 @@ enum OperationType {
         (void (^)(BOOL success))completionHandler {
   DCHECK([NSThread isMainThread]);
 
+  // TODO(shreyasv): Consult the delegate here if it wants to |DELETE| instead.
+  // crbug.com/480654.
+
   base::WeakNSObject<CRWBrowsingDataStore> weakSelf(self);
   [self performOperationWithType:STASH
             browsingDataManagers:[self allBrowsingDataManagers]
diff --git a/ios/web/ios_web.gyp b/ios/web/ios_web.gyp
index 146592d..da17880 100644
--- a/ios/web/ios_web.gyp
+++ b/ios/web/ios_web.gyp
@@ -143,6 +143,7 @@
         'public/browser_url_rewriter.h',
         'public/browsing_data_partition.h',
         'public/crw_browsing_data_store.h',
+        'public/crw_browsing_data_store_delegate.h',
         'public/cert_policy.h',
         'public/cert_store.h',
         'public/certificate_policy_cache.h',
diff --git a/ios/web/public/crw_browsing_data_store.h b/ios/web/public/crw_browsing_data_store.h
index c23f388..e957b65 100644
--- a/ios/web/public/crw_browsing_data_store.h
+++ b/ios/web/public/crw_browsing_data_store.h
@@ -8,6 +8,7 @@
 #import <Foundation/Foundation.h>
 
 #import "base/ios/block_types.h"
+#import "ios/web/public/crw_browsing_data_store_delegate.h"
 
 namespace web {
 class BrowserState;
@@ -47,6 +48,9 @@ enum CRWBrowsingDataStoreMode {
 - (instancetype)initWithBrowserState:(web::BrowserState*)browserState
     NS_DESIGNATED_INITIALIZER;
 
+// The delegate that is consulted when the mode needs to change.
+@property(nonatomic, weak) id<CRWBrowsingDataStoreDelegate> delegate;
+
 // The mode that the CRWBrowsingDataStore is in. KVO compliant.
 @property(nonatomic, assign, readonly) CRWBrowsingDataStoreMode mode;
 
@@ -54,6 +58,9 @@ enum CRWBrowsingDataStoreMode {
 // web::WebViewCounter class is implemented. crbug.com/480507
 
 // Changes the mode to |ACTIVE|.
+// if there is no delegate present, the default behavior of this method is to
+// restore browsing data from |browserState|'s stash path to the canonical path
+// where web views read/write browsing data to.
 // |completionHandler| is called on the main thread. This block has no return
 // value and takes a single BOOL argument that indicates whether or not the
 // the mode was successfully changed to |ACTIVE|.
@@ -64,6 +71,10 @@ enum CRWBrowsingDataStoreMode {
         (void (^)(BOOL success))completionHandler;
 
 // Changes the mode to |INACTIVE|.
+// if there is no delegate present, the default behavior of this method is to
+// value and takes a single BOOL argument that indicates whether or not the
+// stash browsing data created by the web view in to |browserState|'s stash
+// path.
 // |completionHandler| is called on the main thread. This block has no return
 // value and takes a single BOOL argument that indicates whether or not the
 // the mode was successfully changed to |INACTIVE|.
diff --git a/ios/web/public/crw_browsing_data_store_delegate.h b/ios/web/public/crw_browsing_data_store_delegate.h
new file mode 100644
index 0000000..22b2352
--- /dev/null
+++ b/ios/web/public/crw_browsing_data_store_delegate.h
@@ -0,0 +1,53 @@
+// 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 IOS_WEB_CRW_BROWSING_DATA_STORE_DELEGATE_H_
+#define IOS_WEB_CRW_BROWSING_DATA_STORE_DELEGATE_H_
+
+#import <Foundation/Foundation.h>
+
+@class CRWBrowsingDataStore;
+
+namespace web {
+
+// The policy to pass back to the CRWBrowsingDataStore when the
+// CRWBrowsingDataStore's mode wants to become |ACTIVE|.
+typedef NS_ENUM(NSUInteger, BrowsingDataStoreMakeActivePolicy) {
+  // Adopt browsing data to the canonical path where web views store their
+  // browsing data.
+  ADOPT = 1,
+  // Restore browsing data from the stash path. This is the default policy and
+  // is the same policy that is used if the delegate was not implemented.
+  RESTORE,
+};
+
+// The policy to pass back to the CRWBrowsingDataStore when the
+// CRWBrowsingDataStore's mode wants to become |INACTIVE|.
+typedef NS_ENUM(NSUInteger, BrowsingDataStoreMakeInactivePolicy) {
+  // Delete browsing data created by the web views.
+  DELETE = 1,
+  // Stash browsing data created by the web views. This is the default policy
+  // and is the same policy that is used if the delegate was not implemented.
+  STASH,
+};
+
+}  // namespace web
+
+// The CRWBrowsingDataStoreDelegate has methods that can override the default
+// behavior of a CRWBrowsingDataStoreMode when a mode change occurs.
+@protocol CRWBrowsingDataStoreDelegate<NSObject>
+
+// Called when a CRWBrowsingDataStore wants to change its mode to |ACTIVE|.
+- (web::BrowsingDataStoreMakeActivePolicy)
+    decideMakeActiveOperationPolicyForBrowsingDataStore:
+        (CRWBrowsingDataStore*)browsingDataStore;
+
+// Called when a CRWBrowsingDataStore wants to change its mode to |INACTIVE|.
+- (web::BrowsingDataStoreMakeActivePolicy)
+    decideMakeInactiveOperationPolicyForBrowsingDataStore:
+        (CRWBrowsingDataStore*)browsingDataStore;
+
+@end
+
+#endif  // IOS_WEB_CRW_BROWSING_DATA_STORE_DELEGATE_H_