fuchsia: Don't CHECK(false) on EnableInProcessStackDumping.

In-process capture of exceptions doesn't work well because there's no
symbols on-device. Instead, just let the system crashlogger output a
backtrace that the run script can symbolize.

Bug: chromium:731217
Change-Id: I9a509a29e55229a5d8675c9bdc890b50a6a9bfb9
Reviewed-on: https://chromium-review.googlesource.com/619947
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47440}

src/base/debug/stack_trace_fuchsia.cc

@@ -14,7 +14,10 @@ namespace base {
 namespace debug {
 
 bool EnableInProcessStackDumping() {
-  CHECK(false);  // TODO(fuchsia): Port, https://crbug.com/731217.
+  // The system crashlogger captures and prints backtraces which are then
+  // symbolized by a host-side script that runs addr2line. Because symbols are
+  // not available on device, there's not much use in implementing in-process
+  // capture.
   return false;
 }