Closing a guest session clears all browsing history.

chrome/browser/browsing_data/browsing_data_remover.cc

Index: chrome/browser/browsing_data/browsing_data_remover.cc
diff --git a/chrome/browser/browsing_data/browsing_data_remover.cc b/chrome/browser/browsing_data/browsing_data_remover.cc
index 4e3b3653e819a978ef320fb89b8fbd26efa739f6..94da5cfd79f34f21142a98f2886611bf10a8653c 100644
--- a/chrome/browser/browsing_data/browsing_data_remover.cc
+++ b/chrome/browser/browsing_data/browsing_data_remover.cc
@@ -647,8 +647,9 @@ void BrowsingDataRemover::RemoveImpl(int remove_mask,
         content::StoragePartition::REMOVE_DATA_MASK_WEBRTC_IDENTITY;
 
 #if defined(ENABLE_EXTENSIONS)
-    // Clear the ephemeral apps cache.
-    EphemeralAppService::Get(profile_)->ClearCachedApps();
+    // Clear the ephemeral apps cache. This is NULL while testing.
+    if (EphemeralAppService::Get(profile_))

[Peter Kasting, 2015/02/10 21:43:36]

Get() is named as if it's expensive, implying we should use a temporary here
(or, if this isn't expensive, consider renaming to get()).

[Mike Lerman, 2015/02/10 21:53:32]

It's a BrowserContextKeyedService, which follows the pattern of having a static
Get(Profile*) method. (It's an expensive transaction to access a BCKS that
exists, nor to check if one exists).

[Peter Kasting, 2015/02/10 21:58:10]

Did you mean to say, it's NOT an expensive transaction?

I might just use a temp here anyway to avoid giving the reader any pause.

[Mike Lerman, 2015/02/11 15:15:32]

I did mean to say in-expensive. Serves me right for dashing out responses
quickly before I head out the door.
Ok, temp created.

+      EphemeralAppService::Get(profile_)->ClearCachedApps();
 #endif
   }