Add support building with OpenMAX DL FFT for WebAudio

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 636 matching lines @@
       # require server-side APIs may fail to work if no keys are
       # provided.
       #
       # Note that if you are building an official build or if
       # use_official_google_api_keys has been set to 1 (explicitly or
       # implicitly), these values will be ignored and the official
       # keys will be used instead.
       'google_api_key%': '',
       'google_default_client_id%': '',
       'google_default_client_secret%': '',
+
+      # Whether Android uses OpenMAX DL FFT.  Default is no.
+      'use_openmax_dl_fft%': 0,
     },
 
     # Copy conditionally-set variables out one scope.
     'branding%': '<(branding)',
     'buildtype%': '<(buildtype)',
     'target_arch%': '<(target_arch)',
     'host_arch%': '<(host_arch)',
     'toolkit_views%': '<(toolkit_views)',
     'ui_compositor_image_transport%': '<(ui_compositor_image_transport)',
     'use_aura%': '<(use_aura)',
@@ skipping 237 matching lines @@
     # Set Thumb compilation flags.
     'arm_thumb%': 0,
 
     # Set ARM fpu compilation flags (only meaningful if armv7==1 and
     # arm_neon==0).
     'arm_fpu%': 'vfpv3',
 
     # Set ARM float abi compilation flag.
     'arm_float_abi%': 'softfp',
 
+    # Enable use of OpenMAX DL FFT routines.
+    'use_openmax_dl_fft%': '<(use_openmax_dl_fft)',
+    
     # Enable new NPDevice API.
     'enable_new_npdevice_api%': 0,
 
     # Enable EGLImage support in OpenMAX
     'enable_eglimage%': 1,
 
     # Enable a variable used elsewhere throughout the GYP files to determine
     # whether to compile in the sources for the GPU plugin / process.
     'enable_gpu%': 1,
 
@@ skipping 3182 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',
   },
 }