Enable Unified Media View by default.

Unified Media View is enabled by default to make it testable on canary
channel.

Bug: 1033531
Test: Run browser_tests
Change-Id: If11307e1add5606decd4e05265d8dfab43fbaeab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2045290
Commit-Queue: Noel Gordon <noel@chromium.org>
Auto-Submit: Naoki Fukino <fukino@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739769}

chromeos/constants/chromeos_features.cc

@@ -252,7 +252,7 @@ const base::Feature kSplitSettingsSync{"SplitSettingsSync",
 // Enables unified media view in Files app to browse recently-modified media
 // files from local local, Google Drive, and Android.
 const base::Feature kUnifiedMediaView{"UnifiedMediaView",
-                                      base::FEATURE_DISABLED_BY_DEFAULT};
+                                      base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enables the updated cellular activation UI; see go/cros-cellular-design.
 const base::Feature kUpdatedCellularActivationUi{