ambient: Add API to fetch preview images of live album

Bug: b/160753530
Test: manual
Change-Id: I4edae4b329f17919ad25aca3800adf79861e6f1e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2287273Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789276}

ash/ambient/backdrop/ambient_backend_controller_impl.cc

@@ -199,6 +199,16 @@ void AmbientBackendControllerImpl::UpdateSettings(
       weak_factory_.GetWeakPtr(), settings, std::move(callback)));
 }
 
+void AmbientBackendControllerImpl::FetchSettingPreview(
+    int preview_width,
+    int preview_height,
+    OnSettingPreviewFetchedCallback callback) {
+  Shell::Get()->ambient_controller()->RequestAccessToken(
+      base::BindOnce(&AmbientBackendControllerImpl::FetchSettingPreviewInternal,
+                     weak_factory_.GetWeakPtr(), preview_width, preview_height,
+                     std::move(callback)));
+}
+
 void AmbientBackendControllerImpl::FetchPersonalAlbums(
     int banner_width,
     int banner_height,
@@ -337,6 +347,47 @@ void AmbientBackendControllerImpl::OnUpdateSettings(
   std::move(callback).Run(success);
 }
 
+void AmbientBackendControllerImpl::FetchSettingPreviewInternal(
+    int preview_width,
+    int preview_height,
+    OnSettingPreviewFetchedCallback callback,
+    const std::string& gaia_id,
+    const std::string& access_token) {
+  if (gaia_id.empty() || access_token.empty()) {
+    LOG(ERROR) << "Failed to fetch access token";
+    // Returns a dummy instance to indicate the failure.
+    std::move(callback).Run(/*preview_urls=*/{});
+    return;
+  }
+
+  BackdropClientConfig::Request request =
+      backdrop_client_config_.CreateFetchSettingPreviewRequest(
+          preview_width, preview_height, gaia_id, access_token);
+  std::unique_ptr<network::ResourceRequest> resource_request =
+      CreateResourceRequest(request);
+  auto backdrop_url_loader = std::make_unique<BackdropURLLoader>();
+  auto* loader_ptr = backdrop_url_loader.get();
+  loader_ptr->Start(
+      std::move(resource_request), /*request_body=*/base::nullopt,
+      NO_TRAFFIC_ANNOTATION_YET,
+      base::BindOnce(&AmbientBackendControllerImpl::OnSettingPreviewFetched,
+                     weak_factory_.GetWeakPtr(), std::move(callback),
+                     std::move(backdrop_url_loader)));
+}
+
+void AmbientBackendControllerImpl::OnSettingPreviewFetched(
+    OnSettingPreviewFetchedCallback callback,
+    std::unique_ptr<BackdropURLLoader> backdrop_url_loader,
+    std::unique_ptr<std::string> response) {
+  DCHECK(backdrop_url_loader);
+
+  // Parse the |SettingPreviewResponse| out from the response string.
+  // Note that the |preview_urls| can be empty if the parsing has failed.
+  std::vector<std::string> preview_urls =
+      BackdropClientConfig::ParseSettingPreviewResponse(*response);
+  std::move(callback).Run(std::move(preview_urls));
+}
+
 void AmbientBackendControllerImpl::FetchPersonalAlbumsInternal(
     int banner_width,
     int banner_height,

ash/ambient/backdrop/ambient_backend_controller_impl.h

@@ -31,6 +31,9 @@ class AmbientBackendControllerImpl : public AmbientBackendController {
   void GetSettings(GetSettingsCallback callback) override;
   void UpdateSettings(const AmbientSettings& settings,
                       UpdateSettingsCallback callback) override;
+  void FetchSettingPreview(int preview_width,
+                           int preview_height,
+                           OnSettingPreviewFetchedCallback callback) override;
   void FetchPersonalAlbums(int banner_width,
                            int banner_height,
                            int num_albums,
@@ -69,6 +72,17 @@ class AmbientBackendControllerImpl : public AmbientBackendController {
                         std::unique_ptr<BackdropURLLoader> backdrop_url_loader,
                         std::unique_ptr<std::string> response);
 
+  void FetchSettingPreviewInternal(int preview_width,
+                                   int preview_height,
+                                   OnSettingPreviewFetchedCallback callback,
+                                   const std::string& gaia_id,
+                                   const std::string& access_token);
+
+  void OnSettingPreviewFetched(
+      OnSettingPreviewFetchedCallback callback,
+      std::unique_ptr<BackdropURLLoader> backdrop_url_loader,
+      std::unique_ptr<std::string> response);
+
   void FetchPersonalAlbumsInternal(int banner_width,
                                    int banner_height,
                                    int num_albums,

ash/ambient/fake_ambient_backend_controller_impl.cc

@@ -60,6 +60,16 @@ void FakeAmbientBackendControllerImpl::UpdateSettings(
       FROM_HERE, base::BindOnce(std::move(callback), /*success=*/true));
 }
 
+void FakeAmbientBackendControllerImpl::FetchSettingPreview(
+    int preview_width,
+    int preview_height,
+    OnSettingPreviewFetchedCallback callback) {
+  std::vector<std::string> urls = {kFakeUrl};
+  // Pretend to respond asynchronously.
+  base::SequencedTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::BindOnce(std::move(callback), urls));
+}
+
 void FakeAmbientBackendControllerImpl::FetchPersonalAlbums(
     int banner_width,
     int banner_height,

ash/ambient/fake_ambient_backend_controller_impl.h

@@ -25,6 +25,9 @@ class ASH_EXPORT FakeAmbientBackendControllerImpl
   void GetSettings(GetSettingsCallback callback) override;
   void UpdateSettings(const AmbientSettings& settings,
                       UpdateSettingsCallback callback) override;
+  void FetchSettingPreview(int preview_width,
+                           int preview_height,
+                           OnSettingPreviewFetchedCallback) override;
   void FetchPersonalAlbums(int banner_width,
                            int banner_height,
                            int num_albums,

ash/public/cpp/ambient/ambient_backend_controller.h

@@ -80,6 +80,8 @@ class ASH_PUBLIC_EXPORT AmbientBackendController {
   using GetSettingsCallback =
       base::OnceCallback<void(const base::Optional<AmbientSettings>& settings)>;
   using UpdateSettingsCallback = base::OnceCallback<void(bool success)>;
+  using OnSettingPreviewFetchedCallback =
+      base::OnceCallback<void(const std::vector<std::string>& preview_urls)>;
   using OnPersonalAlbumsFetchedCallback =
       base::OnceCallback<void(PersonalAlbums)>;
 
@@ -106,6 +108,11 @@ class ASH_PUBLIC_EXPORT AmbientBackendController {
   virtual void UpdateSettings(const AmbientSettings& settings,
                               UpdateSettingsCallback callback) = 0;
 
+  // Fetch preview images for live album.
+  virtual void FetchSettingPreview(int preview_width,
+                                   int preview_height,
+                                   OnSettingPreviewFetchedCallback) = 0;
+
   virtual void FetchPersonalAlbums(int banner_width,
                                    int banner_height,
                                    int num_albums,