Refactor visual diff action

- Pass `Config` to `SendGuiMessage()`
- Return `absl::Status`
- Use `absl::FunctionRef<>`
- Clean up how the path to "Program Files" is obtained

PiperOrigin-RevId: 637559132
Change-Id: Icee7464935d75ce8706edb70b69c237ca3afd853

util/process.cc

@@ -40,6 +40,8 @@
 #include <cstdlib>
 #include <cstring>
 #include <locale>  // IWYU pragma: keep
+#include <string>
+#include <vector>
 
 #include "third_party/absl/base/attributes.h"  // IWYU pragma: keep
 #include "third_party/absl/status/status.h"
@@ -285,4 +287,19 @@ absl::StatusOr<std::string> GetCommonAppDataDirectory(
   return path;
 }
 
+absl::StatusOr<std::string> GetProgramFilesDirectory() {
+#if defined(_WIN32)
+  char buffer[MAX_PATH] = {0};
+  if (SHGetFolderPath(/*hwndOwner=*/0, CSIDL_PROGRAM_FILES, /*hToken=*/0,
+                      /*dwFlags=*/0, buffer) != S_OK) {
+    return absl::UnknownError(GetLastOsError());
+  }
+  return std::string(buffer);
+#elif defined(__APPLE__)
+  return "/Applications";
+#else
+  return "/opt";
+#endif
+}
+
 }  // namespace security::binexport

util/process.h

@@ -54,7 +54,7 @@ absl::StatusOr<std::string> GetModuleFilename();
 //   Windows  C:\Users\<User>\AppData\Roaming\BinDiff
 //            %AppData%\BinDiff
 //   Linux    /home/<User>/.bindiff
-//   macOS    /Users/<User>/Library/Application Supprt/BinDiff
+//   macOS    /Users/<User>/Library/Application Support/BinDiff
 absl::StatusOr<std::string> GetOrCreateAppDataDirectory(
     absl::string_view product_name);
 
@@ -70,6 +70,16 @@ absl::StatusOr<std::string> GetOrCreateAppDataDirectory(
 absl::StatusOr<std::string> GetCommonAppDataDirectory(
     absl::string_view product_name);
 
+// Returns the platform-specific per-machine directory for application packages.
+// Returns one of these paths:
+//   OS       Typical value
+//   ------------------------------------------------------
+//   Windows  C:\Program Files
+//            %ProgramFiles%
+//   Linux    /opt
+//   macOS    /Applications
+absl::StatusOr<std::string> GetProgramFilesDirectory();
+
 }  // namespace security::binexport
 
 #endif  // UTIL_PROCESS_H_