ui: Cleanup class/struct forward declarations

chrome/browser/component_updater/widevine_cdm_component_installer.cc

Index: chrome/browser/component_updater/widevine_cdm_component_installer.cc
diff --git a/chrome/browser/component_updater/widevine_cdm_component_installer.cc b/chrome/browser/component_updater/widevine_cdm_component_installer.cc
index fed96ad1cd6d7de6476f1cededf66cbd5a783d11..5598540eaeb5a9cfc1875f66d1c7b49030259b10 100644
--- a/chrome/browser/component_updater/widevine_cdm_component_installer.cc
+++ b/chrome/browser/component_updater/widevine_cdm_component_installer.cc
@@ -250,8 +250,9 @@ class WidevineCdmComponentInstallerTraits : public ComponentInstallerTraits {
   // The following methods override ComponentInstallerTraits.
   bool SupportsGroupPolicyEnabledComponentUpdates() const override;
   bool RequiresNetworkEncryption() const override;
-  bool OnCustomInstall(const base::DictionaryValue& manifest,
-                               const base::FilePath& install_dir) override;
+  update_client::CrxInstaller::Result OnCustomInstall(
+      const base::DictionaryValue& manifest,
+      const base::FilePath& install_dir) override;
   bool VerifyInstallation(
       const base::DictionaryValue& manifest,
       const base::FilePath& install_dir) const override;
@@ -288,10 +289,11 @@ bool WidevineCdmComponentInstallerTraits::RequiresNetworkEncryption() const {
   return false;
 }
 
-bool WidevineCdmComponentInstallerTraits::OnCustomInstall(
+update_client::CrxInstaller::Result
+WidevineCdmComponentInstallerTraits::OnCustomInstall(
     const base::DictionaryValue& manifest,
     const base::FilePath& install_dir) {
-  return true;
+  return update_client::CrxInstaller::Result(0);
 }
 
 // Once the CDM is ready, check the CDM adapter.