Don't omit frame pointers in profiling Android GN builds.

This CL makes sure that frame pointers (used for fast stack unwinding)
are not omitted when enable_profiling is true. There are two changes:

1. Don't add -fomit-frame-pointer flag (Android-specific change).

2. Add -fno-omit-frame-pointer flag even in debug builds. This is needed
   for Android where debug builds are optimized too (-Os).

BUG=602701

Review-Url: https://codereview.chromium.org/1965143003
Cr-Original-Commit-Position: refs/heads/master@{#393320}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 14430a4de781aca8e67f6ec7b8893647d7ee26d9

config/compiler/BUILD.gn

@@ -241,11 +241,12 @@ config("compiler") {
   # Non-Mac Posix compiler flags setup.
   # -----------------------------------
   if (is_posix && !(is_mac || is_ios)) {
-    if (enable_profiling && !is_debug) {
-      cflags += [
-        "-fno-omit-frame-pointer",
-        "-g",
-      ]
+    if (enable_profiling) {
+      # Explicitly ask for frame pointers. Otherwise they are omitted when
+      # any optimization level is used (and Android debug builds use -Os).
+      cflags += [ "-fno-omit-frame-pointer" ]
+      if (!is_debug) {
+        cflags += [ "-g" ]
 
         if (enable_full_stack_frames_for_profiling) {
           cflags += [
@@ -254,6 +255,7 @@ config("compiler") {
           ]
         }
       }
+    }
 
     defines += [ "_FILE_OFFSET_BITS=64" ]
 
@@ -1209,7 +1211,7 @@ if (is_win) {
     # We don't omit frame pointers on arm64 since they are required
     # to correctly unwind stackframes which contain system library
     # function frames (crbug.com/391706).
-    if (!using_sanitizer && target_cpu != "arm64") {
+    if (!using_sanitizer && !enable_profiling && target_cpu != "arm64") {
       common_optimize_on_cflags += [ "-fomit-frame-pointer" ]
     }
 
@@ -1299,7 +1301,7 @@ config("no_optimize") {
     # We don't omit frame pointers on arm64 since they are required
     # to correctly unwind stackframes which contain system library
     # function frames (crbug.com/391706).
-    if (!using_sanitizer && target_cpu != "arm64") {
+    if (!using_sanitizer && !enable_profiling && target_cpu != "arm64") {
       cflags += [ "-fomit-frame-pointer" ]
     }