Explicitly specify whether to emit frame pointers by default.

base/debug/stack_trace.h

Index: base/debug/stack_trace.h
diff --git a/base/debug/stack_trace.h b/base/debug/stack_trace.h
index 8bb369571302739d56b0873afc8ff5855448f14f..f864c64adeffad8e0542e13ca1e8ca5d538933f4 100644
--- a/base/debug/stack_trace.h
+++ b/base/debug/stack_trace.h
@@ -24,28 +24,6 @@ struct _EXCEPTION_POINTERS;
 struct _CONTEXT;
 #endif
 
-// Fast stack trace capture using frame pointers is only available under POSIX
-// platforms, and only for certain architectures, and only when frame pointers
-// are enabled in the build.
-#if defined(OS_POSIX)
-#if BUILDFLAG(ENABLE_PROFILING) || !defined(NDEBUG)
-
-#if defined(__i386__) || defined(__x86_64__)
-#define HAVE_TRACE_STACK_FRAME_POINTERS 1
-#elif defined(__arm__) && !defined(__thumb__)
-#define HAVE_TRACE_STACK_FRAME_POINTERS 1
-#else  //  defined(__arm__) && !defined(__thumb__)

[Primiano Tucci (use gerrit), 2017/03/30 13:15:03]

where did this logic go?
The deal here is that we can use frame pointers only when building in ARM (i.e.
non-thumb mode), which happens IIRC with profiling=1.
Makes sense to move this to build-time, but at very least I'd expect something
conditioned by arm_use_thumb or similar, which I don't see here.

[erikchen, 2017/03/30 22:12:47]

The !thumb logic was added here:
https://bugs.chromium.org/p/chromium/issues/detail?id=602701#c5

Either:
1) We can't emit frame_pointers on thumb. I would hope that clang throws an
error when we try to force frame pointers anyways. In this case, we should
update the logic in compiler.gni to accurately reflect this.

2) For some reason, stack walking with frame pointers doesn't work on thumb. In
this case, we should update the stack-walking logic /conditionals to indicate
this. It has nothing to do with whether stacks have frame pointers.

3) Everything works fine on thumb, and this CL doesn't need to change.

-#define HAVE_TRACE_STACK_FRAME_POINTERS 0
-#endif  //  defined(__arm__) && !defined(__thumb__)
-
-#else  //  BUILDFLAG(ENABLE_PROFILING) || !defined(NDEBUG)
-#define HAVE_TRACE_STACK_FRAME_POINTERS 0
-#endif  //  BUILDFLAG(ENABLE_PROFILING) || !defined(NDEBUG)
-
-#else  // defined(OS_POSIX)
-#define HAVE_TRACE_STACK_FRAME_POINTERS 0
-#endif  // defined(OS_POSIX)
-
 namespace base {
 namespace debug {