Roll breakpad to 9c4671f2e3a63c0f155d9b2511192d0b5fa7f760

Retry bringing in symupload native symbols support on Mac (with fix from
previous roll attempt in https://crrev.com/c/2380139).

9c4671f Change JSON serialization error check.
bdac77a file_id_unittest: avoid system()
5640e57 CopyFile: add a C++ API
c6d49c4 linux: Fix leak when the offset of memory_mapped_file is greater than 0
039c4c9 Add a .clang-format file to give us local control over Chromium style.
9c38ab7 Add native symbol uploads to Mac OS symupload tool.
62d9272 linux: Fix segfault when there is no section header in ELF file
087795c processor: subtract 1 from return pointers while scanning
014e842 Escape more characters in Mac OS sym-upload-v2 debug_file strings.

BUG=1021742
R=mark@chromium.org, nbilling@google.com

Change-Id: If54fbc92bf1253c25cb8ca0ef15494a506a9d793
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2426729Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Michael Moss <mmoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809899}

DEPS

@@ -836,7 +836,7 @@ deps = {
   },
 
   'src/third_party/breakpad/breakpad':
-    Var('chromium_git') + '/breakpad/breakpad.git' + '@' + 'e3a62dc5502dec6ab451061769d7efaf5b7ffba8',
+    Var('chromium_git') + '/breakpad/breakpad.git' + '@' + '9c4671f2e3a63c0f155d9b2511192d0b5fa7f760',
 
   'src/third_party/byte_buddy': {
       'packages': [