[fsp] Add support for observing entries and notifying about changes.
This patch adds:
1. Flag supports_notify_tag to chrome.fsp.mount().
2. Method chrome.fsp.Notify() to notify about changes of observed entries.
3. Events chrome.fsp.OnObserveDirectory and OnUnobserveEntry.
Missing things, to be added in a separate patch:
1. Glueing chrome.fsp.Notify to the C++ layer properly, not with fake data.
2. Saving and restoring observed entries together with tags from preferences.
TEST=unit_test: *FileSystemProviderProvidedFileSystem*,
*FileSystemProvider*Observe*, *FileSystemProvider*Unobserve*
BUG=248427
Review URL: https://codereview.chromium.org/625463002
Cr-Commit-Position: refs/heads/master@{#299058}
diff --git a/extensions/browser/extension_function_histogram_value.h b/extensions/browser/extension_function_histogram_value.h
index 78465ca8..de9e001 100644
--- a/extensions/browser/extension_function_histogram_value.h
+++ b/extensions/browser/extension_function_histogram_value.h
@@ -964,6 +964,7 @@
COPRESENCESOCKET_SEND,
COPRESENCESOCKET_DISCONNECT,
BOOKMARKMANAGERPRIVATE_SETVERSION,
+ FILESYSTEMPROVIDER_NOTIFY,
// Last entry: Add new entries above and ensure to update
// tools/metrics/histograms/histograms.xml.
ENUM_BOUNDARY
