[ios] Use no-op CallWithEHFrame for 32 bit.

Cronet still builds 32-bit.

Bug: 1100434
Change-Id: I62511f8a5dae409cf8f85423a479c22283a3f9b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2274781
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#783758}

base/mac/call_with_eh_frame.cc

@@ -12,6 +12,7 @@
 namespace base {
 namespace mac {
 
+#if defined(__x86_64__) || defined(__aarch64__)
 extern "C" _Unwind_Reason_Code __gxx_personality_v0(int,
                                                     _Unwind_Action,
                                                     uint64_t,
@@ -42,5 +43,11 @@ _Unwind_Reason_Code CxxPersonalityRoutine(
   return __gxx_personality_v0(version, actions, exception_class,
                               exception_object, context);
 }
+#else  // !defined(__x86_64__) && !defined(__aarch64__)
+// No implementation exists, so just call the block directly.
+void CallWithEHFrame(void (^block)(void)) {
+  block();
+}
+#endif  // defined(__x86_64__) || defined(__aarch64__)
 }  // namespace mac
 }  // namespace base

base/mac/call_with_eh_frame_asm.S

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#if defined(__x86_64__) || defined(__aarch64__)
+
 // base::mac::CallWithEHFrame(void () block_pointer)
 #define CALL_WITH_EH_FRAME __ZN4base3mac15CallWithEHFrameEU13block_pointerFvvE
 
@@ -127,3 +129,5 @@ Lcall_site_table_end:
 
 Ltypes_table_base:
   .p2align 2
+
+#endif  // defined(__x86_64__) || defined(__aarch64__)