Add brotli content-encoding filter.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 579 matching lines @@
 
       # Enables support for background apps.
       'enable_background%': 1,
 
       # Enable the task manager by default.
       'enable_task_manager%': 1,
 
       # Enables used resource whitelist generation; disabled by default.
       'enable_resource_whitelist_generation%': 0,
 
+      # Enable BROTLI support by default.
+      'disable_brotli_support%': 0,

[Ryan Sleevi, 2015/12/17 01:04:40]

There is strong resistance towards adding system-wide flags like this.

Can you explain more why this is necessary, and whether you see this as
short-term or long-term?

[eustas, 2015/12/17 16:44:54]

This flag was added in response to a request to make it possible completely
disable brotli in a build.
So I've decided to mimic FTP and File support.
I'm OK to remove it (it was planned as a short-term, until feature is fully
launched).

[Ryan Sleevi, 2015/12/17 22:49:33]

Right, we're generally trying not to add build flags like that, since every
permutation adds to complexity and testing.

For example, it's unclear which is "supported" or not, what bots we have
building either, etc.

+
       # Enable FILE support by default.
       'disable_file_support%': 0,
 
       # Enable FTP support by default.
       'disable_ftp_support%': 0,
 
       # Use of precompiled headers on Windows.
       #
       # This variable may be explicitly set to 1 (enabled) or 0
       # (disabled) in ~/.gyp/include.gypi or via the GYP command line.
@@ skipping 241 matching lines @@
         ['branding=="Chrome" and chromeos==1', {
           'enable_hotwording%': 1,
         }],
 
         ['OS=="android"', {
           'enable_webrtc%': 1,
         }],
 
         ['OS=="ios"', {
           'configuration_policy%': 0,
+          'disable_brotli_support%': 1,
           'disable_ftp_support%': 1,
           'enable_extensions%': 0,
           'cld2_table_size%': 0,
           'enable_basic_printing%': 0,
           'enable_print_preview%': 0,
           'enable_session_service%': 0,
           'enable_spellcheck%': 0,
           'enable_themes%': 0,
           'enable_webrtc%': 0,
           'notifications%': 0,
@@ skipping 340 matching lines @@
     'linux_use_debug_fission%': '<(linux_use_debug_fission)',
     'use_canvas_skia%': '<(use_canvas_skia)',
     'test_isolation_mode%': '<(test_isolation_mode)',
     'enable_basic_printing%': '<(enable_basic_printing)',
     'enable_print_preview%': '<(enable_print_preview)',
     'enable_spellcheck%': '<(enable_spellcheck)',
     'use_browser_spellchecker%': '<(use_browser_spellchecker)',
     'cld_version%': '<(cld_version)',
     'cld2_table_size%': '<(cld2_table_size)',
     'enable_captive_portal_detection%': '<(enable_captive_portal_detection)',
+    'disable_brotli_support%': '<(disable_brotli_support)',
     'disable_file_support%': '<(disable_file_support)',
     'disable_ftp_support%': '<(disable_ftp_support)',
     'enable_task_manager%': '<(enable_task_manager)',
     'sas_dll_path%': '<(sas_dll_path)',
     'wix_path%': '<(wix_path)',
     'use_libjpeg_turbo%': '<(use_libjpeg_turbo)',
     'use_system_libjpeg%': '<(use_system_libjpeg)',
     'android_channel%': '<(android_channel)',
     'icu_use_data_file_flag%': '<(icu_use_data_file_flag)',
     'gyp_managed_install%': 0,
@@ skipping 1799 matching lines @@
       }],
       ['enable_captive_portal_detection==1', {
         'defines': ['ENABLE_CAPTIVE_PORTAL_DETECTION=1'],
       }],
       ['enable_app_list==1', {
         'defines': ['ENABLE_APP_LIST=1'],
       }],
       ['enable_settings_app==1', {
         'defines': ['ENABLE_SETTINGS_APP=1'],
       }],
+      ['disable_brotli_support==1', {
+        'defines': ['DISABLE_BROTLI_SUPPORT=1'],
+      }],
       ['disable_file_support==1', {
         'defines': ['DISABLE_FILE_SUPPORT=1'],
       }],
       ['disable_ftp_support==1', {
         'defines': ['DISABLE_FTP_SUPPORT=1'],
       }],
       ['enable_supervised_users==1', {
         'defines': ['ENABLE_SUPERVISED_USERS=1'],
       }],
       ['enable_mdns==1', {
@@ skipping 3359 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',
   },
 }