Bring Audio Share and Tab Share Default On

Desktop share with audio and Desktop share using a chrome tab
as source are two new functionality developed.

Previously the functionalities are behind the flags
--enable-audio-support-for-desktop-share
--enable-tab-for-desktop-share

This CL changes the flags to be disable flags, namely:
--disable-audio-support-for-desktop-share
--disable-tab-for-desktop-share

In another word, we bring the functionalities on by default.

BUG=597539,597540

Review URL: https://codereview.chromium.org/1838623002

Cr-Commit-Position: refs/heads/master@{#384656}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 665d78f..0bb490f 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1775,14 +1775,16 @@
     {"enable-scroll-anchoring", IDS_FLAGS_ENABLE_SCROLL_ANCHORING_NAME,
      IDS_FLAGS_ENABLE_SCROLL_ANCHORING_DESCRIPTION, kOsAll,
      FEATURE_VALUE_TYPE(features::kScrollAnchoring)},
-    {"enable-audio-support-for-desktop-share",
-     IDS_FLAG_ENABLE_AUDIO_FOR_DESKTOP_SHARE,
-     IDS_FLAG_ENABLE_AUDIO_FOR_DESKTOP_SHARE_DESCRIPTION, kOsAll,
-     SINGLE_VALUE_TYPE(switches::kEnableAudioSupportForDesktopShare)},
+    {"disable-audio-support-for-desktop-share",
+     IDS_FLAG_DISABLE_AUDIO_FOR_DESKTOP_SHARE,
+     IDS_FLAG_DISABLE_AUDIO_FOR_DESKTOP_SHARE_DESCRIPTION, kOsAll,
+     SINGLE_VALUE_TYPE(switches::kDisableAudioSupportForDesktopShare)},
 #if defined(ENABLE_EXTENSIONS)
-    {"enable-tab-for-desktop-share", IDS_FLAG_ENABLE_TAB_FOR_DESKTOP_SHARE,
-     IDS_FLAG_ENABLE_TAB_FOR_DESKTOP_SHARE_DESCRIPTION, kOsAll,
-     SINGLE_VALUE_TYPE(extensions::switches::kEnableTabForDesktopShare)},
+    {"tab-for-desktop-share", IDS_FLAG_DISABLE_TAB_FOR_DESKTOP_SHARE,
+     IDS_FLAG_DISABLE_TAB_FOR_DESKTOP_SHARE_DESCRIPTION, kOsAll,
+     ENABLE_DISABLE_VALUE_TYPE(
+         extensions::switches::kEnableTabForDesktopShare,
+         extensions::switches::kDisableTabForDesktopShare)},
 #endif
 #if defined(OS_ANDROID)
     {"enable-ntp-snippets", IDS_FLAGS_ENABLE_NTP_SNIPPETS_NAME,