Linux cflag changes:...

build/common.gypi

 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
@@ skipping 210 matching lines @@
               '_DEBUG',
             ],
             'cflags': [
               '-O0',
               '-g',
             ],
           },
           'Release': {
             'cflags': [
               '-O2',
+              # Don't emit the GCC version ident directives, they just end up
+              # in the .comment section taking up binary size.
+              '-fno-ident',
+              # Put data and code in their own sections, so that unused symbols
+              # can be removed at link time with --gc-sections.
+              '-fdata-sections',
+              '-ffunction-sections',
             ],
           },
         },
         'variants': {
           'coverage': {
             'cflags': ['-fprofile-arcs', '-ftest-coverage'],
             'ldflags': ['-fprofile-arcs'],
           },
           'profile': {
             'cflags': ['-pg', '-g'],
@@ skipping 149 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }