Reland "ambient: cache two backup photos"

This is a reland of a81c2688

Original change's description:
> ambient: cache two backup photos
>
> Handle failure cases better by having backup photos on disk.
> Refresh these images after user logs in.
>
> BUG=b:167332126
>
> Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
> Change-Id: I7046a20ed9606638e851247f8c213d112af6c30b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429585
> Commit-Queue: Jeffrey Young <cowmoo@chromium.org>
> Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
> Reviewed-by: Tao Wu <wutao@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#813904}

Bug: b:167332126
Bug: b:170312454
Change-Id: If5306f627e1a6dfb5e4eb37842a470d17968ad4e
Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2458894
Commit-Queue: Jeffrey Young <cowmoo@chromium.org>
Reviewed-by: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814968}

ash/ambient/ambient_constants.h

@@ -24,6 +24,10 @@ constexpr base::TimeDelta kTopicFetchInterval =
 constexpr base::TimeDelta kPhotoRefreshInterval =
     base::TimeDelta::FromSeconds(60);
 
+// The default interval to fetch backup cache photos.
+constexpr base::TimeDelta kBackupPhotoRefreshDelay =
+    base::TimeDelta::FromMinutes(5);
+
 // The default interval to refresh weather.
 constexpr base::TimeDelta kWeatherRefreshInterval =
     base::TimeDelta::FromMinutes(5);
@@ -47,6 +51,10 @@ constexpr char kPhotoDetailsFileExt[] = ".txt";
 // Directory name of ambient mode.
 constexpr char kAmbientModeDirectoryName[] = "ambient-mode";
 
+constexpr char kAmbientModeCacheDirectoryName[] = "cache";
+
+constexpr char kAmbientModeBackupCacheDirectoryName[] = "backup";
+
 // The buffer time to use the access token.
 constexpr base::TimeDelta kTokenUsageTimeBuffer =
     base::TimeDelta::FromMinutes(10);

ash/ambient/ambient_controller.cc

@@ -323,6 +323,11 @@ void AmbientController::OnLockStateChanged(bool locked) {
   }
 }
 
+void AmbientController::OnFirstSessionStarted() {
+  if (IsAmbientModeEnabled())
+    ambient_photo_controller_.ScheduleFetchBackupImages();
+}
+
 void AmbientController::OnPowerStatusChanged() {
   if (ambient_ui_model_.ui_visibility() != AmbientUiVisibility::kShown) {
     // No action needed if ambient screen is not shown.

ash/ambient/ambient_controller.h

@@ -63,6 +63,7 @@ class ASH_EXPORT AmbientController
 
   // SessionObserver:
   void OnLockStateChanged(bool locked) override;
+  void OnFirstSessionStarted() override;
 
   // PowerStatus::Observer:
   void OnPowerStatusChanged() override;

ash/ambient/ambient_photo_controller.h

@@ -44,6 +44,11 @@ class ASH_EXPORT AmbientURLLoader {
   virtual void Download(
       const std::string& url,
       network::SimpleURLLoader::BodyAsStringCallback callback) = 0;
+
+  virtual void DownloadToFile(
+      const std::string& url,
+      network::SimpleURLLoader::DownloadToFileCompleteCallback callback,
+      const base::FilePath& file_path) = 0;
 };
 
 // A wrapper class of |data_decoder| to decode the photo raw data. In the test,
@@ -87,6 +92,8 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
   void StartScreenUpdate();
   void StopScreenUpdate();
 
+  void ScheduleFetchBackupImages();
+
   AmbientBackendModel* ambient_backend_model() {
     return &ambient_backend_model_;
   }
@@ -95,6 +102,10 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
     return photo_refresh_timer_;
   }
 
+  const base::OneShotTimer& backup_photo_refresh_timer_for_testing() const {
+    return backup_photo_refresh_timer_;
+  }
+
   // AmbientBackendModelObserver:
   void OnTopicsChanged() override;
 
@@ -112,6 +123,14 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
 
   void ScheduleRefreshImage();
 
+  // Create the backup cache directory and start downloading images.
+  void PrepareFetchBackupImages();
+
+  // Download backup cache images.
+  void FetchBackupImages();
+
+  void OnBackupImageFetched(base::FilePath file_path);
+
   void GetScreenUpdateInfo();
 
   // Return a topic to download the image.
@@ -178,11 +197,16 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
 
   void FetchImageForTesting();
 
+  void FetchBackupImagesForTesting();
+
   AmbientBackendModel ambient_backend_model_;
 
   // The timer to refresh photos.
   base::OneShotTimer photo_refresh_timer_;
 
+  // The timer to refresh backup cache photos.
+  base::OneShotTimer backup_photo_refresh_timer_;
+
   // The timer to refresh weather information.
   base::RepeatingTimer weather_refresh_timer_;
 
@@ -194,6 +218,10 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
   // to read from the next cached file by increasing this index by 1.
   int cache_index_for_display_ = 0;
 
+  // Current index of backup cached image to display when no other cached images
+  // are available.
+  size_t backup_cache_index_for_display_ = 0;
+
   // Current index of cached image to save for the latest downloaded photo.
   // The write command could fail. This index will increase 1 no matter writing
   // successfully or not. But theoretically we could not to change this index if
@@ -207,6 +235,8 @@ class ASH_EXPORT AmbientPhotoController : public AmbientBackendModelObserver {
   // read cached images.
   int retries_to_read_from_cache_ = kMaxNumberOfCachedImages;
 
+  int backup_retries_to_read_from_cache_ = 0;
+
   // Backoff for fetch topics retries.
   net::BackoffEntry fetch_topic_retry_backoff_;
 

ash/ambient/backdrop/ambient_backend_controller_impl.cc

@@ -4,6 +4,7 @@
 
 #include "ash/ambient/backdrop/ambient_backend_controller_impl.h"
 
+#include <array>
 #include <string>
 #include <utility>
 #include <vector>
@@ -24,6 +25,7 @@
 #include "base/logging.h"
 #include "base/optional.h"
 #include "base/time/time.h"
+#include "chromeos/assistant/internal/ambient/backdrop_client_config.h"
 #include "chromeos/assistant/internal/proto/google3/backdrop/backdrop.pb.h"
 #include "chromeos/constants/chromeos_features.h"
 #include "components/prefs/pref_service.h"
@@ -459,6 +461,11 @@ void AmbientBackendControllerImpl::FetchWeather(FetchWeatherCallback callback) {
                                    std::move(backdrop_url_loader)));
 }
 
+const std::array<const char*, 2>&
+AmbientBackendControllerImpl::GetBackupPhotoUrls() const {
+  return chromeos::ambient::kBackupPhotoUrls;
+}
+
 void AmbientBackendControllerImpl::FetchScreenUpdateInfoInternal(
     int num_topics,
     OnScreenUpdateInfoFetchedCallback callback,

ash/ambient/backdrop/ambient_backend_controller_impl.h

@@ -5,6 +5,7 @@
 #ifndef ASH_AMBIENT_BACKDROP_AMBIENT_BACKEND_CONTROLLER_IMPL_H_
 #define ASH_AMBIENT_BACKDROP_AMBIENT_BACKEND_CONTROLLER_IMPL_H_
 
+#include <array>
 #include <memory>
 #include <string>
 #include <utility>
@@ -48,6 +49,7 @@ class AmbientBackendControllerImpl : public AmbientBackendController {
       OnSettingsAndAlbumsFetchedCallback callback) override;
   void SetPhotoRefreshInterval(base::TimeDelta interval) override;
   void FetchWeather(FetchWeatherCallback callback) override;
+  const std::array<const char*, 2>& GetBackupPhotoUrls() const override;
 
  private:
   using BackdropClientConfig = chromeos::ambient::BackdropClientConfig;

ash/ambient/test/ambient_ash_test_base.cc

@@ -21,9 +21,11 @@
 #include "ash/session/session_controller_impl.h"
 #include "ash/shell.h"
 #include "base/callback.h"
+#include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #include "base/sequenced_task_runner.h"
+#include "base/threading/scoped_blocking_call.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/time/time.h"
 #include "chromeos/constants/chromeos_features.h"
@@ -48,18 +50,42 @@ class TestAmbientURLLoaderImpl : public AmbientURLLoader {
   void Download(
       const std::string& url,
       network::SimpleURLLoader::BodyAsStringCallback callback) override {
-    std::string data = data_ ? *data_ : "test";
     // Pretend to respond asynchronously.
     base::SequencedTaskRunnerHandle::Get()->PostDelayedTask(
         FROM_HERE,
         base::BindOnce(std::move(callback),
-                       std::make_unique<std::string>(data)),
+                       std::make_unique<std::string>(data_ ? *data_ : "test")),
         base::TimeDelta::FromMilliseconds(1));
   }
+  void DownloadToFile(
+      const std::string& url,
+      network::SimpleURLLoader::DownloadToFileCompleteCallback callback,
+      const base::FilePath& file_path) override {
+    if (!data_) {
+      base::SequencedTaskRunnerHandle::Get()->PostTask(
+          FROM_HERE, base::BindOnce(std::move(callback), base::FilePath()));
+      return;
+    }
+
+    if (!WriteFile(file_path, *data_)) {
+      LOG(WARNING) << "error writing file to file_path: " << file_path;
+
+      base::SequencedTaskRunnerHandle::Get()->PostTask(
+          FROM_HERE, base::BindOnce(std::move(callback), base::FilePath()));
+      return;
+    }
+
+    base::SequencedTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::BindOnce(std::move(callback), file_path));
+  }
 
   void SetData(std::unique_ptr<std::string> data) { data_ = std::move(data); }
 
  private:
+  bool WriteFile(const base::FilePath& file_path, const std::string& data) {
+    base::ScopedBlockingCall blocking(FROM_HERE, base::BlockingType::MAY_BLOCK);
+    return base::WriteFile(file_path, data);
+  }
   // If not null, will return this data.
   std::unique_ptr<std::string> data_;
 };
@@ -352,6 +378,10 @@ void AmbientAshTestBase::FetchImage() {
   photo_controller()->FetchImageForTesting();
 }
 
+void AmbientAshTestBase::FetchBackupImages() {
+  photo_controller()->FetchBackupImagesForTesting();
+}
+
 void AmbientAshTestBase::SetUrlLoaderData(std::unique_ptr<std::string> data) {
   auto* url_loader_ = static_cast<TestAmbientURLLoaderImpl*>(
       photo_controller()->get_url_loader_for_testing());
@@ -359,7 +389,7 @@ void AmbientAshTestBase::SetUrlLoaderData(std::unique_ptr<std::string> data) {
   url_loader_->SetData(std::move(data));
 }
 
-void AmbientAshTestBase::SeteImageDecoderImage(const gfx::ImageSkia& image) {
+void AmbientAshTestBase::SetImageDecoderImage(const gfx::ImageSkia& image) {
   auto* image_decoder = static_cast<TestAmbientImageDecoderImpl*>(
       photo_controller()->get_image_decoder_for_testing());
 

ash/ambient/test/ambient_ash_test_base.h

@@ -141,9 +141,11 @@ class AmbientAshTestBase : public AshTestBase {
 
   void FetchImage();
 
+  void FetchBackupImages();
+
   void SetUrlLoaderData(std::unique_ptr<std::string> data);
 
-  void SeteImageDecoderImage(const gfx::ImageSkia& image);
+  void SetImageDecoderImage(const gfx::ImageSkia& image);
 
  private:
   base::test::ScopedFeatureList scoped_feature_list_;

ash/public/cpp/ambient/ambient_backend_controller.h

@@ -5,6 +5,7 @@
 #ifndef ASH_PUBLIC_CPP_AMBIENT_AMBIENT_BACKEND_CONTROLLER_H_
 #define ASH_PUBLIC_CPP_AMBIENT_AMBIENT_BACKEND_CONTROLLER_H_
 
+#include <array>
 #include <string>
 #include <vector>
 
@@ -156,6 +157,10 @@ class ASH_PUBLIC_EXPORT AmbientBackendController {
 
   // Fetch the weather information.
   virtual void FetchWeather(FetchWeatherCallback) = 0;
+
+  // Get stock photo urls to cache in advance in case Ambient mode is started
+  // without internet access.
+  virtual const std::array<const char*, 2>& GetBackupPhotoUrls() const = 0;
 };
 
 }  // namespace ash

ash/public/cpp/ambient/fake_ambient_backend_controller_impl.cc

@@ -4,6 +4,7 @@
 
 #include "ash/public/cpp/ambient/fake_ambient_backend_controller_impl.h"
 
+#include <array>
 #include <utility>
 
 #include "ash/public/cpp/ambient/ambient_backend_controller.h"
@@ -26,6 +27,9 @@ constexpr char kFakeUrl[] = "chrome://ambient";
 
 constexpr char kFakeDetails[] = "fake-photo-attribution";
 
+constexpr std::array<const char*, 2> kFakeBackupPhotoUrls = {kFakeUrl,
+                                                             kFakeUrl};
+
 AmbientSettings CreateFakeSettings() {
   AmbientSettings settings;
   settings.topic_source = kTopicSource;
@@ -154,6 +158,11 @@ void FakeAmbientBackendControllerImpl::FetchWeather(
   std::move(callback).Run(weather_info_);
 }
 
+const std::array<const char*, 2>&
+FakeAmbientBackendControllerImpl::GetBackupPhotoUrls() const {
+  return kFakeBackupPhotoUrls;
+}
+
 void FakeAmbientBackendControllerImpl::ReplyFetchSettingsAndAlbums(
     bool success) {
   if (!pending_fetch_settings_albums_callback_)

ash/public/cpp/ambient/fake_ambient_backend_controller_impl.h

@@ -5,6 +5,8 @@
 #ifndef ASH_PUBLIC_CPP_AMBIENT_FAKE_AMBIENT_BACKEND_CONTROLLER_IMPL_H_
 #define ASH_PUBLIC_CPP_AMBIENT_FAKE_AMBIENT_BACKEND_CONTROLLER_IMPL_H_
 
+#include <array>
+
 #include "ash/public/cpp/ambient/ambient_backend_controller.h"
 #include "ash/public/cpp/ash_public_export.h"
 #include "base/callback.h"
@@ -40,6 +42,7 @@ class ASH_PUBLIC_EXPORT FakeAmbientBackendControllerImpl
       OnSettingsAndAlbumsFetchedCallback callback) override;
   void SetPhotoRefreshInterval(base::TimeDelta interval) override;
   void FetchWeather(FetchWeatherCallback callback) override;
+  const std::array<const char*, 2>& GetBackupPhotoUrls() const override;
 
   // Simulate to reply the request of FetchSettingsAndAlbums().
   // If |success| is true, will return fake data.

chrome/browser/ui/ash/ambient/ambient_client_impl_unittest.cc

@@ -32,7 +32,6 @@ class AmbientClientImplTest : public ChromeAshTestBase {
         chromeos::features::kAmbientModeFeature);
     // Needed by ash.
     ambient_client_ = std::make_unique<AmbientClientImpl>();
-    AshTestBase::SetUp();
 
     ASSERT_TRUE(data_dir_.CreateUniqueTempDir());
     profile_manager_ = std::make_unique<TestingProfileManager>(
@@ -48,6 +47,8 @@ class AmbientClientImplTest : public ChromeAshTestBase {
         std::make_unique<IdentityTestEnvironmentProfileAdaptor>(profile_);
     user_manager_enabler_ = std::make_unique<user_manager::ScopedUserManager>(
         std::make_unique<chromeos::FakeChromeUserManager>());
+
+    AshTestBase::SetUp();
   }
 
   void TearDown() override {