Enable FIXED_POINT and -O3 for Opus when building for ARM.

third_party/opus/opus.gyp

Index: third_party/opus/opus.gyp
diff --git a/third_party/opus/opus.gyp b/third_party/opus/opus.gyp
index 3b37f42b795afd53725485d7f70ac96d51dd4d70..1c6cad2ddb837e7ec980f6e99860ddd87ec3828b 100644
--- a/third_party/opus/opus.gyp
+++ b/third_party/opus/opus.gyp
@@ -3,16 +3,27 @@
 # found in the LICENSE file.
 
 {
+  'target_defaults': {
+    'variables': {
+      # Performance gains are substantial on ARM (v7,v8) with -O3 over the
+      # default -Os configured in common.gypi.
+      'release_optimize': '3',
+      'debug_optimize': '3',
+    },
+  },
   'variables': {
     'conditions': [
-      ['((OS=="android" or chromeos==1) and target_arch=="arm") or (OS=="ios" and target_arch=="armv7")', {
+      ['target_arch=="arm" or target_arch=="armv7" or target_arch=="arm64"', {
         'use_opus_fixed_point%': 1,
-        'use_opus_arm_optimization%': 1,
       }, {
         'use_opus_fixed_point%': 0,
+      }],
+      ['target_arch=="arm" or target_arch=="armv7"', {
+        'use_opus_arm_optimization%': 1,
+      }, {
         'use_opus_arm_optimization%': 0,
       }],
-      ['(OS=="android" or chromeos==1) and target_arch=="arm"', {
+      ['target_arch=="arm"', {
         'use_opus_rtcd%': 1,
       }, {
         'use_opus_rtcd%': 0,
@@ -55,7 +66,7 @@
             4334,  # Disable 32-bit shift warning in src/opus_encoder.c .
           ],
         }],
-        [ 'os_posix==1 and OS!="android"', {
+        ['os_posix==1 and OS!="android"', {
           # Suppress a warning given by opus_decoder.c that tells us
           # optimizations are turned off.
           'cflags': [