Web Share: Enable by default on Chrome OS and Windows

Enabling the Web Share APIs (navigator.Share) functionality on Windows
and Chrome OS.

Intent to Ship:
https://groups.google.com/a/chromium.org/g/blink-dev/c/fJ8n9kTbna4/m/i8mMlc0jAgAJ

Bug: 770595
Change-Id: I2dea1ab64be53b36d53901f2f46d95483555d4df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2583104
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835993}

chrome/common/chrome_features.cc

@@ -912,7 +912,7 @@ const base::Feature kWebRtcRemoteEventLogGzipped{
 
 #if defined(OS_WIN) || BUILDFLAG(IS_CHROMEOS_ASH)
 // Enables Web Share (navigator.share)
-const base::Feature kWebShare{"WebShare", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kWebShare{"WebShare", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 // Enables setting time limit for Chrome and PWA's on child user device.