Add ffmpeg (chromium's branch) to third_party for use in mojo media.

build/config/BUILDCONFIG.gn

 # Copyright (c) 2013 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.
 
 if (target_os == "") {
   target_os = host_os
 }
 
 if (target_cpu == "") {
   if (target_os == "android") {
@@ skipping 408 matching lines @@
 # Optimizations and debug checking.
 if (is_debug) {
   _native_compiler_configs += [ "//build/config:debug" ]
   _default_optimization_config = "//build/config/compiler:no_optimize"
 } else {
   _native_compiler_configs += [ "//build/config:release" ]
   _default_optimization_config = "//build/config/compiler:optimize"
 }
 _native_compiler_configs += [ _default_optimization_config ]
 
+# //third_party/ffmpeg/BUILD.gn wants to remove this, add it. Does nothing.

[brettw, 2015/10/13 21:35:36]

You should migrate to Chrome's configuration for this, where the default
optimization config is added unconditionally and this expands to the current
default behavior. We do the same for symbols, etc now since it makes it much
easier to do what ffmpeg is doing. If you don't migrate to this, you'll lose
optimization for the targets that opt into max-optimization.

+_native_compiler_configs += [ "//build/config/compiler:default_optimization" ]
+
 # If it wasn't manually set, set to an appropriate default.
 if (symbol_level == -1) {
   # Linux is slowed by having symbols as part of the target binary, whereas
   # Mac and Windows have them separate, so in Release Linux, default them off.
   if (is_debug || !is_linux) {
     symbol_level = 2
   } else if (is_asan || is_lsan || is_tsan || is_msan) {
     # Sanitizers require symbols for filename suppressions to work.
     symbol_level = 1
   } else {
@@ skipping 351 matching lines @@
       }
       if (defined(invoker.testonly)) {
         testonly = invoker.testonly
       }
       if (defined(invoker.visibility)) {
         visibility = invoker.visibility
       }
     }
   }
 }