Reland "Turn on Media History by default"

This is a reland of ccf0e2f9

Fixes TSAN issue in the constructor of sql::Database
by moving it to the main thread.

Original change's description:
> Turn on Media History by default
>
> BUG=1024351
>
> Change-Id: Id01595e63f5f776a226087741ef602ba30b80328
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2295224
> Auto-Submit: Becca Hughes <beccahughes@chromium.org>
> Commit-Queue: Tommy Steimel <steimel@chromium.org>
> Reviewed-by: Tommy Steimel <steimel@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#787954}

Bug: 1024351
Change-Id: I19be665637f5c28261f7197547ddc5fe6671127e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2296884Reviewed-by: Tommy Steimel <steimel@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788312}

chrome/browser/media/history/media_history_store.cc

@@ -174,6 +174,8 @@ MediaHistoryStore::MediaHistoryStore(
     scoped_refptr<base::UpdateableSequencedTaskRunner> db_task_runner)
     : db_task_runner_(db_task_runner),
       db_path_(GetDBPath(profile)),
+      db_(std::make_unique<sql::Database>()),
+      meta_table_(std::make_unique<sql::MetaTable>()),
       origin_table_(new MediaHistoryOriginTable(db_task_runner_)),
       playback_table_(new MediaHistoryPlaybackTable(db_task_runner_)),
       session_table_(new MediaHistorySessionTable(db_task_runner_)),
@@ -186,7 +188,14 @@ MediaHistoryStore::MediaHistoryStore(
       feed_items_table_(IsMediaFeedsEnabled()
                             ? new MediaHistoryFeedItemsTable(db_task_runner_)
                             : nullptr),
-      initialization_successful_(false) {}
+      initialization_successful_(false) {
+  db_->set_histogram_tag("MediaHistory");
+  db_->set_exclusive_locking();
+
+  // To recover from corruption.
+  db_->set_error_callback(
+      base::BindRepeating(&DatabaseErrorCallback, db_.get(), db_path_));
+}
 
 MediaHistoryStore::~MediaHistoryStore() {
   // The connection pointer needs to be deleted on the DB sequence since there
@@ -304,16 +313,6 @@ void MediaHistoryStore::Initialize(const bool should_reset) {
 MediaHistoryStore::InitResult MediaHistoryStore::InitializeInternal() {
   DCHECK(db_task_runner_->RunsTasksInCurrentSequence());
 
-  db_ = std::make_unique<sql::Database>();
-  db_->set_histogram_tag("MediaHistory");
-  db_->set_exclusive_locking();
-
-  // To recover from corruption.
-  db_->set_error_callback(
-      base::BindRepeating(&DatabaseErrorCallback, db_.get(), db_path_));
-
-  meta_table_ = std::make_unique<sql::MetaTable>();
-
   if (db_path_.empty()) {
     if (IsCancelled() || !db_ || !db_->OpenInMemory()) {
       LOG(ERROR) << "Failed to open the in-memory database.";

media/base/media_switches.cc

@@ -405,7 +405,7 @@ const base::Feature kUseNewMediaCache{"use-new-media-cache",
 
 // Enables using the media history store to store media engagement metrics.
 const base::Feature kUseMediaHistoryStore{"UseMediaHistoryStore",
-                                          base::FEATURE_DISABLED_BY_DEFAULT};
+                                          base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Use R16 texture for 9-16 bit channel instead of half-float conversion by CPU.
 const base::Feature kUseR16Texture{"use-r16-texture",