[v8] Add LTO support for Android Chromium.

build/toolchain.gypi

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 73 matching lines @@
     'v8_toolset_for_d8%': 'target',
 
     'host_os%': '<(OS)',
     'werror%': '-Werror',
     # For a shared library build, results in "libv8-<(soname_version).so".
     'soname_version%': '',
 
     # Allow to suppress the array bounds warning (default is no suppression).
     'wno_array_bounds%': '',
 
+    # Link-Time Optimizations
+    'use_lto%': 0,
+
     'variables': {
       # This is set when building the Android WebView inside the Android build
       # system, using the 'android' gyp backend.
       'android_webview_build%': 0,
     },
     # Copy it out one scope.
     'android_webview_build%': '<(android_webview_build)',
   },
   'conditions': [
     ['host_arch=="ia32" or host_arch=="x64" or clang==1', {
@@ skipping 130 matching lines @@
                       'USE_EABI_HARDFLOAT=1',
                     ],
                   }],
                   [ 'arm_float_abi=="softfp" or arm_float_abi=="default"', {
                     'defines': [
                       'USE_EABI_HARDFLOAT=0',
                     ],
                   }],
                 ],
               }],
+              # Disable LTO for v8
+              # v8 is optimized for speed, which takes precedence over
+              # size optimization in LTO.
+              ['use_lto==1', {
+                'cflags!': [
+                  '-flto',
+                  '-ffat-lto-objects',
+                ],
+              }],
             ],
           }],  # _toolset=="target"
         ],
       }],  # v8_target_arch=="arm"
       ['v8_target_arch=="arm64"', {
         'defines': [
           'V8_TARGET_ARCH_ARM64',
         ],
       }],
       ['v8_target_arch=="ia32"', {
@@ skipping 697 matching lines @@
                 'OptimizeReferences': '2',
                 'EnableCOMDATFolding': '2',
               },
             },
           }],  # OS=="win"
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }