Enable unwind support for all non-official builds

This makes unwind support consistent on Linux (used by
base::debug::StackTrace). A combination of arch-specific toolchain defaults
and arch-specific cflags made the previous behavior inconsistent.

Unwind tables are useful for development and much cheaper than
debuginfo, so enable them for all non-official builds.

TEST=build for ia32, x64, arm (compared defaults & official)
BUG=180975

Review URL: https://codereview.chromium.org/129283003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243919 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -1112,6 +1112,8 @@
     'linux_strip_binary%': 0,
     # Strip the test binaries needed for Linux reliability tests.
     'linux_strip_reliability_tests%': 0,
+    # If we want stack unwind support for backtrace().
+    'unwind_tables%': 1,
 
     # Enable TCMalloc.
     'linux_use_tcmalloc%': 1,
@@ -1289,6 +1291,10 @@
           # symbols from official builds.
           ['(branding=="Chrome" and buildtype=="Official")', {
             'linux_dump_symbols%': 1,
+
+            # Omit unwind support in official builds to save space. We can use
+            # breakpad for these builds.
+            'unwind_tables%': 0,
           }],
         ],
       }],  # os_posix==1 and OS!="mac" and OS!="ios"
@@ -3077,14 +3083,6 @@
                   }],
                 ],
               }],
-              # Can be omitted to reduce output size. Does not seem to affect
-              # crash reporting.
-              ['target_arch=="ia32"', {
-                'cflags': [
-                  '-fno-unwind-tables',
-                  '-fno-asynchronous-unwind-tables',
-                ],
-              }],
             ],
           },
         },
@@ -3562,6 +3560,11 @@
               }],
             ],
           }],
+          ['unwind_tables==1', {
+            'cflags': ['-funwind-tables'],
+          }, {
+            'cflags': ['-fno-unwind-tables', '-fno-asynchronous-unwind-tables'],
+          }],
           ['linux_use_tcmalloc==0 and android_use_tcmalloc==0', {
             'defines': ['NO_TCMALLOC'],
           }],