Enable dynamic color gamut by default

On Android, color gamut changes dynamically with the content being
displayed. This is currently under a Finch flag at 50% canary/dev/beta
and 1% stable. When not enabled, wide color content is not displayed in
wide color.

The Finch experiment has been successful.

This CL enables the feature by default.

R:khushalsagar@chromium.org

Bug: 735658
Change-Id: I9eda388690e3d2fa37d597925c32e38afd7ffe11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370803Reviewed-by: Khushal <khushalsagar@chromium.org>
Commit-Queue: Chris Blume <cblume@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803363}

components/viz/common/features.cc

@@ -42,7 +42,7 @@ const base::Feature kDisableDeJelly{"DisableDeJelly",
 // When wide color gamut content from the web is encountered, promote our
 // display to wide color gamut if supported.
 const base::Feature kDynamicColorGamut{"DynamicColorGamut",
-                                       base::FEATURE_DISABLED_BY_DEFAULT};
+                                       base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 // Viz for WebView architecture.