Revert of Roll clang 277962:278861 (patchset #5 id:80001 of...

Revert of Roll clang 277962:278861 (patchset #5 id:80001 of https://codereview.chromium.org/2241413003/ )

Reason for revert:
This is suspect of breaking Mac 10.9 builder.

See
https://build.chromium.org/p/chromium.mac/builders/Mac10.9%20Tests%20%28dbg%29/builds/28850

Sample logs:
Retrying 1 test (retry #1)
[0817/224954:ERROR:kill_posix.cc(84)] Unable to terminate process group 8687: No such process
[ RUN      ] ThreadTest.StartWithOptions_StackSize
[2060/2060] ThreadTest.StartWithOptions_StackSize (CRASHED)
Retrying 1 test (retry #2)
[0817/224955:ERROR:kill_posix.cc(84)] Unable to terminate process group 8688: No such process
[ RUN      ] ThreadTest.StartWithOptions_StackSize
[2061/2061] ThreadTest.StartWithOptions_StackSize (CRASHED)
Retrying 1 test (retry #3)
[0817/224955:ERROR:kill_posix.cc(84)] Unable to terminate process group 8689: No such process
[ RUN      ] ThreadTest.StartWithOptions_StackSize
[2062/2062] ThreadTest.StartWithOptions_StackSize (CRASHED)
1 test crashed:
    ThreadTest.StartWithOptions_StackSize (../../base/threading/thread_unittest.cc:135)
Tests took 21 seconds.
Additional test environment:
    CHROME_DEVEL_SANDBOX=/opt/chromium/chrome_sandbox
    LANG=en_US.UTF-8
Command: ./base_unittests --brave-new-test-launcher --test-launcher-bot-mode --test-launcher-summary-output=/b/swarm_slave/w/ionk6XHB/output.json

Original issue's description:
> Roll clang 277962:278861
>
> BUG=636558,637866
>
> Committed: https://crrev.com/29ecb32ba7b5ca183782c5f5d2b7a1ae23309edb
> Cr-Commit-Position: refs/heads/master@{#412745}

TBR=rnk@chromium.org,dcheng@chromium.org,dpranke@chromium.org,inferno@chromium.org,hans@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=636558,637866

Review-Url: https://codereview.chromium.org/2249163007
Cr-Commit-Position: refs/heads/master@{#412785}

base/threading/thread_unittest.cc

@@ -137,9 +137,8 @@ TEST_F(ThreadTest, StartWithOptions_StackSize) {
   // Ensure that the thread can work with only 12 kb and still process a
   // message.
   Thread::Options options;
-#if defined(ADDRESS_SANITIZER) || (defined(OS_IOS) && !defined(NDEBUG))
-  // ASan bloats the stack variables and overflows the 12 kb stack. Debug iOS
-  // builds also grow the stack too much.
+#if defined(ADDRESS_SANITIZER)
+  // ASan bloats the stack variables and overflows the 12 kb stack.
   options.stack_size = 24*1024;
 #else
   options.stack_size = 12*1024;

build/config/compiler/BUILD.gn

@@ -1014,10 +1014,13 @@ config("default_warnings") {
 
         # TODO(thakis): https://crbug.com/617318
         "-Wno-nonportable-include-path",
-
-        # TODO(hans): https://crbug.com/637306
-        "-Wno-address-of-packed-member",
       ]
+      if (llvm_force_head_revision) {
+        cflags += [
+          # TODO(hans): https://crbug.com/637306
+          "-Wno-address-of-packed-member",
+        ]
+      }
     }
   }
 }

tools/clang/scripts/update.py

@@ -27,7 +27,7 @@ import zipfile
 # Do NOT CHANGE this if you don't know what you're doing -- see
 # https://chromium.googlesource.com/chromium/src/+/master/docs/updating_clang.md
 # Reverting problematic clang rolls is safe, though.
-CLANG_REVISION = '278861'
+CLANG_REVISION = '277962'
 
 use_head_revision = 'LLVM_FORCE_HEAD_REVISION' in os.environ
 if use_head_revision: