Expose DiscardTab() to MemoryCoordiantor

content/public/browser/memory_coordinator_delegate.h

Index: content/public/browser/memory_coordinator_delegate.h
diff --git a/content/public/browser/memory_coordinator_delegate.h b/content/public/browser/memory_coordinator_delegate.h
index 32758d964fa907e03dd97b30652e92385e700fa8..1c6d694d8bf702701ca977a4fd8d0a8a9c6a88b2 100644
--- a/content/public/browser/memory_coordinator_delegate.h
+++ b/content/public/browser/memory_coordinator_delegate.h
@@ -16,6 +16,10 @@ class CONTENT_EXPORT MemoryCoordinatorDelegate {
 
   // Returns true when a given backgrounded renderer process can be suspended.
   virtual bool CanSuspendBackgroundedRenderer(int render_process_id) = 0;
+
+  // Discards a tab. An implementation should select a low priority tab to
+  // discard.

[kinuko, 2017/02/24 01:29:24]

Is this called when memory is tight? Is the impl supposed to discard one tab at
most?  Is it allowed not to discard tabs if it can't find any candidate?

I see this actually calls TabManager's corresponding method in chrome case, but
might be better to have a bit more descriptive comment for implementors.

[bashi, 2017/02/24 01:40:26]

Updated the comments.

+  virtual void DiscardTab() {}
 };
 
 }  // namespace content