Remove sessions from disk when they are discarded by the OS

Right now sessions data on disk are never deleted. Instead delete them
whenever the app receives a signal that this session can no longer be
brought back via "didDiscardSceneSessions" appdelegate.

This is done by adding a new method to BrowsingDataCommands protocol
and allowing the mainController to conform to it.

Bug: 1114847
Change-Id: I767f75c996fa8554943c09f84c9c637851beee32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2347248
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797908}

ios/chrome/app/application_delegate/BUILD.gn

@@ -177,6 +177,7 @@ source_set("application_delegate_internal") {
     "//ios/chrome/app/startup",
     "//ios/chrome/browser",
     "//ios/chrome/browser/browser_state",
+    "//ios/chrome/browser/browsing_data",
     "//ios/chrome/browser/crash_report",
     "//ios/chrome/browser/device_sharing",
     "//ios/chrome/browser/feature_engagement",

ios/chrome/app/application_delegate/app_state.h

@@ -98,6 +98,12 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
 // mainChrome instance.
 - (void)applicationWillTerminate:(UIApplication*)application;
 
+// Called when the application discards set of scene sessions, these sessions
+// can no longer be accessed and all their associated data should be destroyed.
+- (void)application:(UIApplication*)application
+    didDiscardSceneSessions:(NSSet<UISceneSession*>*)sceneSessions
+    API_AVAILABLE(ios(13));
+
 // Resumes the session: reinitializing metrics and opening new tab if necessary.
 // User sessions are defined in terms of BecomeActive/ResignActive so that
 // session boundaries include things like turning the screen off or getting a

ios/chrome/app/application_delegate/app_state.mm

@@ -28,6 +28,8 @@
 #import "ios/chrome/app/main_application_delegate.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#include "ios/chrome/browser/browsing_data/browsing_data_remover.h"
+#include "ios/chrome/browser/browsing_data/browsing_data_remover_factory.h"
 #include "ios/chrome/browser/chrome_constants.h"
 #include "ios/chrome/browser/crash_report/breakpad_helper.h"
 #include "ios/chrome/browser/crash_report/crash_keys_helper.h"
@@ -468,6 +470,24 @@ initWithBrowserLauncher:(id<BrowserLauncher>)browserLauncher
   [_startupInformation stopChromeMain];
 }
 
+- (void)application:(UIApplication*)application
+    didDiscardSceneSessions:(NSSet<UISceneSession*>*)sceneSessions
+    API_AVAILABLE(ios(13)) {
+  NSMutableArray<NSString*>* sessionIDs =
+      [NSMutableArray arrayWithCapacity:sceneSessions.count];
+  for (UISceneSession* session in sceneSessions) {
+    [sessionIDs addObject:session.persistentIdentifier];
+  }
+  ChromeBrowserState* browserState =
+      _browserLauncher.interfaceProvider.mainInterface.browserState;
+  BrowsingDataRemoverFactory::GetForBrowserState(browserState)
+      ->RemoveSessionsData(sessionIDs);
+  ChromeBrowserState* incognitoBrowserState =
+      _browserLauncher.interfaceProvider.incognitoInterface.browserState;
+  BrowsingDataRemoverFactory::GetForBrowserState(incognitoBrowserState)
+      ->RemoveSessionsData(sessionIDs);
+}
+
 - (void)willResignActiveTabModel {
   if ([_browserLauncher browserInitializationStage] <
       INITIALIZATION_STAGE_FOREGROUND) {

ios/chrome/app/main_application_delegate.mm

@@ -226,6 +226,7 @@
   ios::GetChromeBrowserProvider()
       ->GetChromeIdentityService()
       ->ApplicationDidDiscardSceneSessions(sceneSessions);
+  [_appState application:application didDiscardSceneSessions:sceneSessions];
 }
 #endif  // BUILDFLAG(IOS_MULTIWINDOW_ENABLED)
 

ios/chrome/browser/browsing_data/BUILD.gn

@@ -20,8 +20,8 @@ source_set("browsing_data") {
   sources = [
     "browsing_data_counter_wrapper.cc",
     "browsing_data_counter_wrapper.h",
-    "browsing_data_remover.cc",
     "browsing_data_remover.h",
+    "browsing_data_remover.mm",
     "browsing_data_remover_factory.h",
     "browsing_data_remover_factory.mm",
     "browsing_data_remover_impl.h",

ios/chrome/browser/browsing_data/browsing_data_remover.h

@@ -5,6 +5,8 @@
 #ifndef IOS_CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_REMOVER_H_
 #define IOS_CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_REMOVER_H_
 
+#import <Foundation/Foundation.h>
+
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
@@ -31,6 +33,9 @@ class BrowsingDataRemover : public KeyedService {
                       BrowsingDataRemoveMask remove_mask,
                       base::OnceClosure callback) = 0;
 
+  // Removes all persisted data for sessions with |session_ids|.
+  virtual void RemoveSessionsData(NSArray<NSString*>* session_ids) = 0;
+
   // Adds/removes |observer| from the list of observers notified when data is
   // removed by BrowsingDataRemover.
   void AddObserver(BrowsingDataRemoverObserver* observer);

ios/chrome/browser/browsing_data/browsing_data_remover.cc → ios/chrome/browser/browsing_data/browsing_data_remover.mm

@@ -2,10 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ios/chrome/browser/browsing_data/browsing_data_remover.h"
+#import "ios/chrome/browser/browsing_data/browsing_data_remover.h"
 
 #include "ios/chrome/browser/browsing_data/browsing_data_remover_observer.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 BrowsingDataRemover::BrowsingDataRemover() = default;
 
 BrowsingDataRemover::~BrowsingDataRemover() = default;

ios/chrome/browser/browsing_data/browsing_data_remover_impl.h

@@ -46,6 +46,7 @@ class BrowsingDataRemoverImpl : public BrowsingDataRemover {
   void Remove(browsing_data::TimePeriod time_period,
               BrowsingDataRemoveMask remove_mask,
               base::OnceClosure callback) override;
+  void RemoveSessionsData(NSArray<NSString*>* session_ids) override;
 
  private:
   // Represents a single removal task. Contains all parameters to execute it.

ios/chrome/browser/browsing_data/browsing_data_remover_impl.mm

@@ -557,6 +557,16 @@ void BrowsingDataRemoverImpl::RemoveImpl(base::Time delete_begin,
       MAX_CHOICE_VALUE);
 }
 
+// Removes directories for sessions with |SessionIDs|
+void BrowsingDataRemoverImpl::RemoveSessionsData(
+    NSArray<NSString*>* session_ids) {
+  [[SessionServiceIOS sharedService]
+                 deleteSessions:session_ids
+      fromBrowserStateDirectory:base::SysUTF8ToNSString(
+                                    browser_state_->GetStatePath()
+                                        .AsUTF8Unsafe())];
+}
+
 // TODO(crbug.com/619783): removing data from WkWebsiteDataStore should be
 // implemented by //ios/web. Once this is available remove this and use the
 // new API.

ios/chrome/browser/browsing_data/fake_browsing_data_remover.h

@@ -17,6 +17,7 @@ class FakeBrowsingDataRemover : public BrowsingDataRemover {
   void Remove(browsing_data::TimePeriod time_period,
               BrowsingDataRemoveMask remove_mask,
               base::OnceClosure callback) override;
+  void RemoveSessionsData(NSArray<NSString*>* session_ids) override;
 };
 
 #endif  // IOS_CHROME_BROWSER_BROWSING_DATA_FAKE_BROWSING_DATA_REMOVER_H_

ios/chrome/browser/browsing_data/fake_browsing_data_remover.mm

@@ -15,3 +15,6 @@ bool FakeBrowsingDataRemover::IsRemoving() const {
 void FakeBrowsingDataRemover::Remove(browsing_data::TimePeriod time_period,
                                      BrowsingDataRemoveMask remove_mask,
                                      base::OnceClosure callback) {}
+
+void FakeBrowsingDataRemover::RemoveSessionsData(
+    NSArray<NSString*>* session_ids) {}

ios/chrome/browser/sessions/session_service_ios.h

@@ -47,6 +47,11 @@
 - (void)deleteLastSessionFileInDirectory:(NSString*)directory
                               completion:(base::OnceClosure)callback;
 
+// Schedule deletion of session directories with |sessionIDs| which resides in
+// a specific browser state |directory|.
+- (void)deleteSessions:(NSArray<NSString*>*)sessionIDs
+    fromBrowserStateDirectory:(NSString*)directory;
+
 // Returns the path of the session file for |directory|.
 + (NSString*)sessionPathForDirectory:(NSString*)directory;
 

ios/chrome/browser/sessions/session_service_ios.mm

@@ -7,6 +7,7 @@
 #import <UIKit/UIKit.h>
 
 #include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/files/file_path.h"
 #include "base/format_macros.h"
 #include "base/location.h"
@@ -44,6 +45,9 @@
 namespace {
 const NSTimeInterval kSaveDelay = 2.5;     // Value taken from Desktop Chrome.
 NSString* const kRootObjectKey = @"root";  // Key for the root object.
+NSString* const kSessionDirectory =
+    @"Sessions";  // The directory name inside BrowserState directory which
+                  // contain all sessions directories.
 }
 
 @implementation NSKeyedUnarchiver (CrLegacySessionCompatibility)
@@ -168,30 +172,52 @@ NSString* const kRootObjectKey = @"root";  // Key for the root object.
 - (void)deleteLastSessionFileInDirectory:(NSString*)directory
                               completion:(base::OnceClosure)callback {
   NSString* sessionPath = [[self class] sessionPathForDirectory:directory];
+  [self deletePaths:[NSArray arrayWithObject:sessionPath]
+         completion:std::move(callback)];
+}
+
+- (void)deleteSessions:(NSArray<NSString*>*)sessionIDs
+    fromBrowserStateDirectory:(NSString*)directory {
+  NSString* sessionsDirectoryPath =
+      [directory stringByAppendingPathComponent:kSessionDirectory];
+  NSMutableArray<NSString*>* paths =
+      [NSMutableArray arrayWithCapacity:sessionIDs.count];
+  for (NSString* sessionID : sessionIDs) {
+    [paths addObject:[sessionsDirectoryPath
+                         stringByAppendingPathComponent:sessionID]];
+  }
+  [self deletePaths:paths completion:base::DoNothing()];
+}
+
++ (NSString*)sessionPathForDirectory:(NSString*)directory {
+  return [directory stringByAppendingPathComponent:@"session.plist"];
+}
+
+#pragma mark - Private methods
+
+// Delete files/folders of the given |paths|.
+- (void)deletePaths:(NSArray<NSString*>*)paths
+         completion:(base::OnceClosure)callback {
   _taskRunner->PostTaskAndReply(
       FROM_HERE, base::BindOnce(^{
         base::ScopedBlockingCall scoped_blocking_call(
             FROM_HERE, base::BlockingType::MAY_BLOCK);
         NSFileManager* fileManager = [NSFileManager defaultManager];
-        if (![fileManager fileExistsAtPath:sessionPath])
-          return;
-
-        NSError* error = nil;
-        if (![fileManager removeItemAtPath:sessionPath error:&error] || error) {
-          CHECK(false) << "Unable to delete session file: "
-                       << base::SysNSStringToUTF8(sessionPath) << ": "
-                       << base::SysNSStringToUTF8([error description]);
+        for (NSString* path : paths) {
+          if (![fileManager fileExistsAtPath:path])
+            continue;
+
+          NSError* error = nil;
+          if (![fileManager removeItemAtPath:path error:&error] || error) {
+            CHECK(false) << "Unable to delete path: "
+                         << base::SysNSStringToUTF8(path) << ": "
+                         << base::SysNSStringToUTF8([error description]);
+          }
         }
       }),
       std::move(callback));
 }
 
-+ (NSString*)sessionPathForDirectory:(NSString*)directory {
-  return [directory stringByAppendingPathComponent:@"session.plist"];
-}
-
-#pragma mark - Private methods
-
 // Do the work of saving on a background thread.
 - (void)performSaveToPathInBackground:(NSString*)sessionPath {
   DCHECK(sessionPath);