[Remote suggestions] Move all decisions to fetch to the scheduler

components/ntp_snippets/remote/remote_suggestions_scheduler.h

Index: components/ntp_snippets/remote/remote_suggestions_scheduler.h
diff --git a/components/ntp_snippets/remote/remote_suggestions_scheduler.h b/components/ntp_snippets/remote/remote_suggestions_scheduler.h
index 7621161a824faf344f39462ac0f59acfc379db69..1c10ec3e34177ef338cb5b1a0811dda6e31a09e6 100644
--- a/components/ntp_snippets/remote/remote_suggestions_scheduler.h
+++ b/components/ntp_snippets/remote/remote_suggestions_scheduler.h
@@ -12,6 +12,23 @@ namespace ntp_snippets {
 // Interface for informing the scheduler.
 class RemoteSuggestionsScheduler {
  public:
+  // Internal triggers to consider fetching content suggestions.
+
+  // Called whenever the remote suggestions provider becomes active (on startup,
+  // or later on).
+  virtual void OnProviderActivated() = 0;
+
+  // Called whenever the remote suggestions provider becomes inactive (on
+  // startup, or later on).
+  virtual void OnProviderInactivated() = 0;
+
+  // Called whenever the remote suggestions provider clears all suggestions.
+  virtual void OnSuggestionsCleared() = 0;
+
+  // Called whenever the remote suggestions provider clears all suggestions
+  // because history gets cleared (and we must not show them any more).
+  virtual void OnHistoryCleared() = 0;
+
   // External triggers to consider fetching content suggestions.
 
   // Called whenever chrome is started warm or the user switches to Chrome.