ui: Cleanup class/struct forward declarations

components/update_client/update_client_errors.h

Index: components/update_client/update_client_errors.h
diff --git a/components/update_client/update_client_errors.h b/components/update_client/update_client_errors.h
index 34a65da4cdaacf6c58dcf051d8482207994fae35..08b13a299f2071223e34229f6653e7642f8e1ba4 100644
--- a/components/update_client/update_client_errors.h
+++ b/components/update_client/update_client_errors.h
@@ -41,29 +41,39 @@ enum class CrxDownloaderError {
 };
 
 // These errors are returned with the |kUnpackError| error category and
-// indicate unpacker, patcher, or install errors.
+// indicate unpacker or patcher error.
 enum class UnpackerError {
   kNone = 0,
-  kInvalidParams,
-  kInvalidFile,
-  kUnzipPathError,
-  kUnzipFailed,
-  kNoManifest,
-  kBadManifest,
-  kBadExtension,
-  kInvalidId,
-  kInstallerError,
-  kIoError,
-  kDeltaVerificationFailure,
-  kDeltaBadCommands,
-  kDeltaUnsupportedCommand,
-  kDeltaOperationFailure,
-  kDeltaPatchProcessFailure,
-  kDeltaMissingExistingFile,
-  kFingerprintWriteFailed,
+  kInvalidParams = 1,
+  kInvalidFile = 2,
+  kUnzipPathError = 3,
+  kUnzipFailed = 4,
+  // kNoManifest = 5,         // Deprecated. Never used.
+  kBadManifest = 6,
+  kBadExtension = 7,
+  kInvalidId = 8,
+  // kInstallerError = 9,     // Deprecated. Don't use.
+  kIoError = 10,
+  kDeltaVerificationFailure = 11,
+  kDeltaBadCommands = 12,
+  kDeltaUnsupportedCommand = 13,
+  kDeltaOperationFailure = 14,
+  kDeltaPatchProcessFailure = 15,
+  kDeltaMissingExistingFile = 16,
+  // kFingerprintWriteFailed = 17,    // Deprecated. Don't use.
 };
 
 // These errors are returned with the |kServiceError| error category and
+// are returned by the component installers.
+enum class InstallError {
+  NONE = 0,
+  FINGERPRINT_WRITE_FAILED = 2,
+  BAD_MANIFEST = 3,
+  GENERIC_ERROR = 9,        // Matches kInstallerError for compatibility.
+  CUSTOM_ERROR_BASE = 100,  // Specific installer errors go above this value.
+};
+
+// These errors are returned with the |kInstallError| error category and
 // indicate critical or configuration errors in the update service.
 enum class ServiceError {
   NONE = 0,