[Fuchsia] Add OnKeyStatesChanged handler

This is the first change in a soft transition change in the
fuchsia.media.drm APIs. The LicenseSession OnKeysChanged event is being
renamed to OnKeyStatesChanged. This adds an identical handler to the
FuchsiaCdm::CdmSession. Implementations will send one or the other, but
not both events.

Bug: fxb/38522
Change-Id: I07b370f18f38b223c11a89bdc68fddc6955a2b21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879521Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Commit-Queue: RJ Ascani <rjascani@google.com>
Cr-Commit-Position: refs/heads/master@{#709288}

media/fuchsia/cdm/fuchsia_cdm.cc

@@ -126,6 +126,8 @@ class FuchsiaCdm::CdmSession {
         fit::bind_member(this, &CdmSession::OnLicenseMessageGenerated);
     session_.events().OnKeysChanged =
         fit::bind_member(this, &CdmSession::OnKeysChanged);
+    session_.events().OnKeyStatesChanged =
+        fit::bind_member(this, &CdmSession::OnKeyStatesChanged);
 
     session_.set_error_handler(
         fit::bind_member(this, &CdmSession::OnSessionError));
@@ -183,6 +185,8 @@ class FuchsiaCdm::CdmSession {
         std::vector<uint8_t>(session_msg.begin(), session_msg.end()));
   }
 
+  // TODO(fxb/38522): Remove this after Fuchsia CDMs have transitioned to
+  // sending OnKeyStatesChanged
   void OnKeysChanged(std::vector<fuchsia::media::drm::KeyInfo> key_info) {
     std::string new_key_id;
     bool has_additional_usable_key = false;
@@ -210,6 +214,35 @@ class FuchsiaCdm::CdmSession {
       on_new_key_.Run(new_key_id);
   }
 
+  void OnKeyStatesChanged(
+      std::vector<fuchsia::media::drm::KeyState> key_states) {
+    std::string new_key_id;
+    bool has_additional_usable_key = false;
+    CdmKeysInfo keys_info;
+    for (const auto& key_state : key_states) {
+      if (!key_state.has_key_id() || !key_state.has_status()) {
+        continue;
+      }
+      CdmKeyInformation::KeyStatus status = ToCdmKeyStatus(key_state.status());
+      has_additional_usable_key |= (status == CdmKeyInformation::USABLE);
+      if (status == CdmKeyInformation::USABLE && new_key_id.empty()) {
+        // The |key_id| is passed to |on_new_key_| to workaround fxb/38253 in
+        // FuchsiaSecureStreamDecryptor. It needs just one valid |key_id|, so it
+        // doesn't matter if |key_info| contains more than one key.
+        // TODO(crbug.com/1012525): Remove the hack once fxb/38253 is resolved.
+        new_key_id.assign(key_state.key_id().begin(), key_state.key_id().end());
+      }
+      keys_info.emplace_back(
+          new CdmKeyInformation(key_state.key_id(), status, 0));
+    }
+
+    session_callbacks_->keys_change_cb.Run(
+        session_id_, has_additional_usable_key, std::move(keys_info));
+
+    if (has_additional_usable_key)
+      on_new_key_.Run(new_key_id);
+  }
+
   void OnSessionError(zx_status_t status) {
     ZX_LOG(ERROR, status) << "Session error.";
     if (result_cb_)