hindsight: Add finch flags for CrOSActionRecorder.

(1) Feature kEnableCrOSActionRecorder is added with param
    "CrOSActionRecorderType" to initialize CrOSActionRecorder.

(2) Used that flag in unit tests.

(3) Associate a Chrome flag enable-cros-action-recorder to the Feature
    so that the Feature can be enabled from chrome flags.

Bug: 1012936
Change-Id: I21cb53b3a2201a7fa959c936ccee32b397708f4e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1859806
Reviewed-by: Tony Yeoman <[email protected]>
Reviewed-by: Xiyuan Xia <[email protected]>
Reviewed-by: Charles . <[email protected]>
Commit-Queue: Charles . <[email protected]>
Auto-Submit: Charles . <[email protected]>
Cr-Commit-Position: refs/heads/master@{#706662}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 6f750c9d8..fc6ba0da 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3374,6 +3374,12 @@
 const char kEnableBackgroundBlurDescription[] =
     "Enables background blur for the Launcher, Shelf, Unified System Tray etc.";
 
+const char kEnableCrOSActionRecorderName[] = "Enable CrOS action recorder";
+const char kEnableCrOSActionRecorderDescription[] =
+    "When enabled, each app launching, file opening, setting change, and url "
+    "visiting will be logged locally into an encrypted file. Should not be "
+    "enabled.";
+
 const char kEnableDiscoverAppName[] = "Enable Discover App";
 const char kEnableDiscoverAppDescription[] =
     "Enable Discover App icon in launcher.";