[cros] Implement WebM encoder/muxer for animated avatar capture.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index a401bcb2de03bd7fa58e198dd0630d96e84831bf..c71d3164e707bddf0a474df29fc652b374e6a37c 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -57,6 +57,8 @@
         '../third_party/libphonenumber/libphonenumber.gyp:libphonenumber',
         '../third_party/libusb/libusb.gyp:libusb',
         '../third_party/libxml/libxml.gyp:libxml',
+        '../third_party/libvpx/libvpx.gyp:libvpx',
+        '../third_party/libyuv/libyuv.gyp:libyuv',
         '../third_party/npapi/npapi.gyp:npapi',
         '../third_party/zlib/zlib.gyp:zlib',
         '../ui/base/strings/ui_strings.gyp:ui_strings',
@@ -502,6 +504,8 @@
         'browser/chromeos/device_settings_provider.h',
         'browser/chromeos/disks/disk_mount_manager.cc',
         'browser/chromeos/disks/disk_mount_manager.h',
+        'browser/chromeos/ebml_writer.cc',
+        'browser/chromeos/ebml_writer.h',
         'browser/chromeos/enrollment_dialog_view.cc',
         'browser/chromeos/enrollment_dialog_view.h',
         'browser/chromeos/enterprise_extension_observer.cc',
@@ -781,6 +785,8 @@
         'browser/chromeos/login/wizard_controller.h',
         'browser/chromeos/login/wizard_screen.cc',
         'browser/chromeos/login/wizard_screen.h',
+        'browser/chromeos/login/webm_encoder.cc',
+        'browser/chromeos/login/webm_encoder.h',
         'browser/chromeos/low_memory_observer.cc',
         'browser/chromeos/low_memory_observer.h',
         'browser/chromeos/media/media_player.cc',