media: Add MediaDrmStorage

chrome/browser/media/android/cdm/media_drm_storage_impl.cc

+// Copyright 2016 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.
+
+#include "chrome/browser/media/android/cdm/media_drm_storage_impl.h"
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/optional.h"
+#include "chrome/browser/profiles/profile.h"

[xhwang, 2017/03/23 05:25:26]

yucliu: This is the only place where this file depend on chrome/. If we can
remove this, I can put this file under components/cdm/browser/ so that it can be
reused by ChromeCast. Do you know how ChromeCast get the PrefService from the
BrowserContext? (see line 92)

[yucliu1, 2017/03/23 16:36:49]

This would be helpful!

https://cs.chromium.org/chromium/src/chromecast/browser/cast_browser_main_par...

We're able to get PrefService in content client. So probably we can pass
PrefService to this class.

+#include "components/pref_registry/pref_registry_syncable.h"
+#include "components/prefs/pref_service.h"
+#include "components/prefs/scoped_user_pref_update.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/web_contents.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+// The storage will be managed by PrefService. All data will be store as a
+// dictionary under the key "media.media_drm_storage". The dictionary is
+// structured as follows:
+//
+// {
+//     $origin: {
+//         "origin_id": $origin_id

[yucliu1, 2017/03/23 01:07:16]

So origin_id is a random string, right? Who's responsible to generate origin_id,
in MediaDrmBridge or here?

[xhwang, 2017/03/23 05:22:06]

Good question. It's just a random string. In theory it can be generated
anywhere. But the tricky part is we could create two MediaDrmBridge instances
for the same origin, both triggering the provisioning flow. In that case, we
should have some locking mechanism to make sure we don't have collision. I need
to think more about this case.

For now, let's forget about |origin_id| and just use the origin. We need to fix
this before removing the flag. 

+//         "creation_time": $provision_time
+//         $session_id: {
+//             "key_set_id": $key_set_id,
+//             "mime_type": $mime_type,
+//             "creation_time": $creation_time
+//         },
+//         # more session_id map...
+//     },
+//     # more origin map...
+// }
+
+namespace chrome {
+
+namespace {
+
+const char kMediaDrmStorage[] = "media.media_drm_storage";
+const char kKeySetId[] = "key_set_id";
+const char kMimeType[] = "mime_type";
+const char kCreationTime[] = "creation_time";
+
+std::unique_ptr<base::DictionaryValue> CreateOriginDictionary() {
+  auto dict = base::MakeUnique<base::DictionaryValue>();
+  // TODO(xhwang): Base64 encode the |key_set_id|?
+  // TODO(xhwang): Add creation time.
+  dict->SetDouble(kCreationTime, base::Time::Now().ToDoubleT());
+  return dict;
+}
+
+std::unique_ptr<base::DictionaryValue> CreateSessionDictionary(
+    const std::vector<uint8_t>& key_set_id,
+    const std::string& mime_type) {
+  auto dict = base::MakeUnique<base::DictionaryValue>();
+  // TODO(xhwang): Base64 encode the |key_set_id|?
+  // TODO(xhwang): Add creation time.
+  dict->SetString(kKeySetId,
+                  std::string(reinterpret_cast<const char*>(key_set_id.data()),
+                              key_set_id.size()));
+  dict->SetString(kMimeType, mime_type);
+  return dict;
+}
+
+}  // namespace
+
+// static
+void MediaDrmStorageImpl::RegisterProfilePrefs(
+    user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterDictionaryPref(kMediaDrmStorage,
+                                   new base::DictionaryValue());
+}
+
+// static
+void MediaDrmStorageImpl::Create(content::RenderFrameHost* render_frame_host,
+                                 media::mojom::MediaDrmStorageRequest request) {
+  DVLOG(2) << __func__;
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(render_frame_host);
+
+  content::WebContents* web_contents =
+      content::WebContents::FromRenderFrameHost(render_frame_host);
+  if (!web_contents)
+    return;
+
+  content::BrowserContext* browser_context = web_contents->GetBrowserContext();
+  if (!browser_context)
+    return;
+
+  Profile* profile = Profile::FromBrowserContext(browser_context);
+  if (!profile)
+    return;
+
+  PrefService* pref_service = profile->GetPrefs();
+  if (!pref_service)
+    return;
+
+  mojo::MakeStrongBinding(base::MakeUnique<MediaDrmStorageImpl>(pref_service),
+                          std::move(request));
+}
+
+MediaDrmStorageImpl::MediaDrmStorageImpl(PrefService* pref_service)
+    : pref_service_(pref_service), weak_factory_(this) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(pref_service);
+}
+
+MediaDrmStorageImpl::~MediaDrmStorageImpl() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+}
+
+void MediaDrmStorageImpl::Initialize(const url::Origin& origin) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!origin.unique());
+  origin_ = origin.Serialize();
+}
+
+void MediaDrmStorageImpl::OnProvisioned(const OnProvisionedCallback& callback) {
+  DVLOG(2) << __func__;
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!origin_.empty());
+
+  DictionaryPrefUpdate update(pref_service_, kMediaDrmStorage);
+  base::DictionaryValue* storage_dict = update.Get();
+  DCHECK(storage_dict);
+
+  // The origin string may contain dots. Do not use path expansion.
+  if (storage_dict->GetDictionaryWithoutPathExpansion(origin_, nullptr)) {
+    DVLOG(1) << __func__
+             << ": Failed to save persistent session data; entry for origin "
+             << origin_ << " already exists.";
+    callback.Run(false);
+    return;
+  }
+
+  storage_dict->SetWithoutPathExpansion(origin_, CreateOriginDictionary());
+  callback.Run(true);
+}
+
+void MediaDrmStorageImpl::SavePersistentSession(
+    const std::string& session_id,
+    const std::vector<uint8_t>& key_set_id,
+    const std::string& mime_type,
+    const SavePersistentSessionCallback& callback) {
+  DVLOG(2) << __func__;
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!origin_.empty());
+
+  DictionaryPrefUpdate update(pref_service_, kMediaDrmStorage);
+  base::DictionaryValue* storage_dict = update.Get();
+  DCHECK(storage_dict);
+
+  base::DictionaryValue* origin_dict = nullptr;
+  // The origin string may contain dots. Do not use path expansion.
+  storage_dict->GetDictionaryWithoutPathExpansion(origin_, &origin_dict);
+  if (!origin_dict) {
+    DVLOG(1) << __func__
+             << ": Failed to save persistent session data; entry for origin "
+             << origin_ << " does not exist.";
+    callback.Run(false);

[yucliu1, 2017/03/23 01:07:16]

A bigger questions here, what should we do if error happens in storage, should
we simply reject everything and clear everything?

[xhwang, 2017/03/23 05:22:06]

In most cases, we should never fail. The only legit case this (and similarly
others) could fail is when we have "clear media licenses" implemented.

For example, when user choose to "clear media licenses", we'll unprovision the
origin, and then remove the "origin dict", in the browser process. At the same
time, SavepersistentSession() is called. Since the origin has been
unprovisioned, the license cannot be used anymore, so we should just do nothing.
The end result will be the same as we store the session first, then remove the
whole origin dict.

But I agree these cases could be tricky and we need to think them through.

+    return;
+  }
+
+  if (origin_dict->GetDictionaryWithoutPathExpansion(session_id, nullptr)) {
+    DVLOG(1) << __func__ << ": Session ID already exists";
+    callback.Run(false);
+    return;
+  }
+
+  origin_dict->SetWithoutPathExpansion(
+      session_id, CreateSessionDictionary(key_set_id, mime_type));
+
+  callback.Run(true);
+}
+
+void MediaDrmStorageImpl::LoadPersistentSession(
+    const std::string& session_id,
+    const LoadPersistentSessionCallback& callback) {
+  DVLOG(2) << __func__;
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!origin_.empty());
+
+  NOTIMPLEMENTED();
+  callback.Run(false, base::nullopt, base::nullopt);
+}
+
+void MediaDrmStorageImpl::RemovePersistentSession(
+    const std::string& session_id,
+    const RemovePersistentSessionCallback& callback) {
+  DVLOG(2) << __func__;
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!origin_.empty());
+
+  NOTIMPLEMENTED();
+  callback.Run(false);
+}
+
+}  // namespace chrome