This update for chromium, gn fixes the following issues:

Changes in chromium:
- Chromium 135.0.7049.52 (stable release 2025-04-01) (boo#1240555)
  * CVE-2025-3066: Use after free in Navigations
  * CVE-2025-3067: Inappropriate implementation in Custom Tabs
  * CVE-2025-3068: Inappropriate implementation in Intents
  * CVE-2025-3069: Inappropriate implementation in Extensions
  * CVE-2025-3070: Insufficient validation of untrusted input in Extensions
  * CVE-2025-3071: Inappropriate implementation in Navigations
  * CVE-2025-3072: Inappropriate implementation in Custom Tabs
  * CVE-2025-3073: Inappropriate implementation in Autofill
  * CVE-2025-3074: Inappropriate implementation in Downloads

Changes in gn:
- Update to version 0.20250306:
  * Remove deps from rust executable to module's pcm files
  * Update test for rust executable deps
  * Add toolchain for cxx modules in TestWithScope
  * Apply the latest clang-format
  * Update reference for {rustdeps}
  * Always generate a .toolchain file even if it is empty.
  * Pass --with-lg-page=16 when building jemalloc for arm64.
  * Remove obsolete debug checks.
  * Make default vs ide version on Windows as 2022
  * Reland "Adds a path_exists() function"
  * Revert "Adds a path_exists() function"
  * Adds a path_exists() function
  * Revert "Speed-up GN with custom OutputStream interface."
  * Speed-up GN with custom OutputStream interface.
  * Add `exec_script_allowlist` to replace `exec_script_whitelist`.
  * Retry ReplaceFile in case of failure
  * Fix crash when NinjaBuildWriter::RunAndWriteFile fails
  * fix include for escape.h
  * fix exit code for gn gen failure
  * misc: Use html.escape instead of cgi.escape
  * Do not copy parent build_dependency_files_ in Scope constructors.
  * Improve error message for duplicated items
  * [rust-project] Always use forward slashes in sysroot paths
  * Update all_dependent_configs docs.
  * set 'no_stamp_files' by default
  * fix a typo
  * Stop using transitional LFS64 APIs
  * do not use tool prefix for phony rule
  * [rust] Add sysroot_src to rust-project.json
  * Implement and enable 'no_stamp_files'
  * Add Target::dependency_output_alias()
  * Add "outputs" to generated_file documentation.
  * Update bug database link.
  * remove a trailing space after variable bindings
  * fix tool name in error
  * remove unused includes
  * Markdown optimization (follow-up)
  * Support link_output, depend_output in Rust linked tools.
  * Properly verify runtime_outputs in rust tool definitions.
  * BugFix: Syntax error in gen.py file
  * generated_file: add output to input deps of stamp
  * Markdown optimization:
  * Revert "Rust: link_output, depend_output and runtime_outputs for dylibs"
  * hint using nogncheck on disallowed includes