ui: Cleanup class/struct forward declarations

components/component_updater/default_component_installer.h

Index: components/component_updater/default_component_installer.h
diff --git a/components/component_updater/default_component_installer.h b/components/component_updater/default_component_installer.h
index 18a87c543f8d486ead78178be7c23ab92886d640..61e6c56e7670df661e4a40603667a39e2411edb1 100644
--- a/components/component_updater/default_component_installer.h
+++ b/components/component_updater/default_component_installer.h
@@ -58,8 +58,9 @@ class ComponentInstallerTraits {
   // require custom installation operations should implement them here.
   // Returns false if a custom operation failed, and true otherwise.
   // Called only from a thread belonging to a blocking thread pool.
-  virtual bool OnCustomInstall(const base::DictionaryValue& manifest,
-                               const base::FilePath& install_dir) = 0;
+  virtual update_client::CrxInstaller::Result OnCustomInstall(
+      const base::DictionaryValue& manifest,
+      const base::FilePath& install_dir) = 0;
 
   // ComponentReady is called in two cases:
   //   1) After an installation is successfully completed.
@@ -115,8 +116,9 @@ class DefaultComponentInstaller : public update_client::CrxInstaller {
 
   // Overridden from ComponentInstaller:
   void OnUpdateError(int error) override;
-  bool Install(const base::DictionaryValue& manifest,
-               const base::FilePath& unpack_path) override;
+  update_client::CrxInstaller::Result Install(
+      const base::DictionaryValue& manifest,
+      const base::FilePath& unpack_path) override;
   bool GetInstalledFile(const std::string& file,
                         base::FilePath* installed_file) override;
   // Only user-level component installations can be uninstalled.
@@ -130,9 +132,10 @@ class DefaultComponentInstaller : public update_client::CrxInstaller {
   // values associated with that installation and returns true; otherwise,
   // returns false.
   bool FindPreinstallation(const base::FilePath& root);
-  bool InstallHelper(const base::DictionaryValue& manifest,
-                     const base::FilePath& unpack_path,
-                     const base::FilePath& install_path);
+  update_client::CrxInstaller::Result InstallHelper(
+      const base::DictionaryValue& manifest,
+      const base::FilePath& unpack_path,
+      const base::FilePath& install_path);
   void StartRegistration(ComponentUpdateService* cus);
   void FinishRegistration(ComponentUpdateService* cus,
                           const base::Closure& callback);