Add Link-Time Optimizations support for Android.

build/android/increase_size_for_speed.gypi

 # Copyright (c) 2014 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.
 
 # This file is meant to be included to optimize a target for speed
 # rather than for size on Android.
 # This is used in some carefully tailored targets and is not meant
 # to be included everywhere. Before adding the template to another target,
 # please ask in chromium-dev@. See crbug.com/411909
 
 {
   'configurations': {
     'Release': {
       'target_conditions': [
         ['_toolset=="target"', {
           'conditions': [
             ['OS=="android"', {
               'cflags!': ['-Os'],
               'cflags': ['-O2'],
             }],
+            # Do not merge -Os and -O2 in LTO

[pasko, 2014/10/10 11:59:21]

s/LTO/LTO./

Also you can briefly explain, like:
All objects that were compiled with LTO will be forced to have the same
optimization flags at link time with a stupid algorithm. Avoid using LTO
simultaneously on -Os and -O2 parts for that reason.

[Fabrice (no longer in Chrome), 2014/10/13 15:45:12]

Done.

+            ['use_lto==1', {

[pasko, 2014/10/10 11:59:21]

maybe this should be called use_lto_os? I understand that there is code
committed to other repos that name this thing 'use_lto'. Maybe put an 'alias' in
common.gypi to have use_lto_os, and use_lto be aliases? Or maybe just an
explanation in the comment there for the start?

[Fabrice (no longer in Chrome), 2014/10/13 15:45:12]

I think it's too late for that at this point. The bot uses use_lto, the other
repos use use_lto. I added a note in common.gypi explaining the difference
between the two.

+              'cflags!': [
+                '-flto',
+                '-ffat-lto-objects',
+              ],
+            }],
+            ['use_lto_o2==1', {
+              'cflags': [
+                '-flto',
+                '-ffat-lto-objects',
+              ],
+            }],
           ],
         }],
       ],
     },
   },
 }