[NTP] Delete local bg image copy when an update arrives from Sync

Incoming updates from Sync override the local image, so the copy should
be deleted.

Bug: 990099
Change-Id: Ia3d2aaecca8ae97d0f2a46a0d00fbb5374a7a4b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1731783
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Reviewed-by: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683838}

chrome/browser/search/instant_service.cc

@@ -419,6 +419,7 @@ void InstantService::UpdateThemeInfo() {
 void InstantService::UpdateBackgroundFromSync() {
   // Any incoming change to synced background data should clear the local image.
   pref_service_->SetBoolean(prefs::kNtpCustomBackgroundLocalToDevice, false);
+  RemoveLocalBackgroundImageCopy();
   UpdateThemeInfo();
 }
 

chrome/browser/search/instant_service_unittest.cc

@@ -454,7 +454,7 @@ TEST_F(InstantServiceTest, SetLocalImage) {
   EXPECT_TRUE(instant_service_->IsCustomBackgroundSet());
 }
 
-TEST_F(InstantServiceTest, SyncPrefOverridesLocalImage) {
+TEST_F(InstantServiceTest, SyncPrefOverridesAndRemovesLocalImage) {
   ASSERT_FALSE(instant_service_->IsCustomBackgroundSet());
   const GURL kUrl("https://www.foo.com/");
 
@@ -472,6 +472,7 @@ TEST_F(InstantServiceTest, SyncPrefOverridesLocalImage) {
 
   EXPECT_TRUE(
       pref_service->GetBoolean(prefs::kNtpCustomBackgroundLocalToDevice));
+  EXPECT_TRUE(base::PathExists(path));
 
   // Update theme info via Sync.
   pref_service->SetUserPref(
@@ -483,6 +484,7 @@ TEST_F(InstantServiceTest, SyncPrefOverridesLocalImage) {
   EXPECT_EQ(kUrl, theme_info->custom_background_url);
   EXPECT_FALSE(
       pref_service->GetBoolean(prefs::kNtpCustomBackgroundLocalToDevice));
+  EXPECT_FALSE(base::PathExists(path));
   EXPECT_TRUE(instant_service_->IsCustomBackgroundSet());
 }