Enable platform echo cancellation through the AudioRecord path.

content/public/common/media_stream_request.h

Index: content/public/common/media_stream_request.h
diff --git a/content/public/common/media_stream_request.h b/content/public/common/media_stream_request.h
index 6e4292044712dfa6358bdb6e1d10399a67297756..c4c838fb6e376a216a3bbc1c979896ff95ee423e 100644
--- a/content/public/common/media_stream_request.h
+++ b/content/public/common/media_stream_request.h
@@ -106,14 +106,15 @@ struct CONTENT_EXPORT MediaStreamDevice {
   // in media::AudioParameters.
   struct AudioDeviceParameters {
     AudioDeviceParameters()
-        : sample_rate(), channel_layout(), frames_per_buffer() {
+        : sample_rate(), channel_layout(), frames_per_buffer(), effects() {
     }
 
     AudioDeviceParameters(int sample_rate, int channel_layout,
-                          int frames_per_buffer)
+        int frames_per_buffer)
         : sample_rate(sample_rate),
           channel_layout(channel_layout),
-          frames_per_buffer(frames_per_buffer) {
+          frames_per_buffer(frames_per_buffer),
+          effects() {
     }
 
     // Preferred sample rate in samples per second for the device.
@@ -129,6 +130,9 @@ struct CONTENT_EXPORT MediaStreamDevice {
     // expected browser side settings and avoid unnecessary buffering.
     // See media::AudioParameters for more.
     int frames_per_buffer;
+
+    // See media::AudioParameters::PlatformEffectsMask.
+    int effects;
   };
 
   // These below two member variables are valid only when the type of device is