commit 24de0d7db7c7f8a4a5a14171a218ac4f1cff1682
author Fady Samuel <fsamuel@google.com> Mon Jan 20 20:24:17 2020 +0000
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> Mon Jan 20 20:24:17 2020 +0000
tree 7dd802c5ed056f5f31f60c89a81a217fc80432c1
parent 88e8ebfbcc70c2c52f1c7ed0f0320d7a5ca86ba4

[components] Generalize Breakpoints StartComponentTree

Prior to this CL, there was no way for a realm to guarantee it can install
breakpoints prior to its children starting. This CL generalizes the
breakpoints StartComponentTree API such that it applies to every realm
that requests a BreakpointsSystem.

This CL makes a number of refactors in order to support generalized
StartComponentTree.

1. BreakpointSystem => BreakpointSystemFactory,
   ScopedBreakpointSystem => BreakpointSystem.

   ScopedBreakpointSystem is no longer a special case. All instances of
   BreakpointSystem have an optional scope. Instead, we have a
   BreakpointSystemFactory that constructs a BreakpointSystem when a
   component is resolved that requests the BreakpointSystem. A
   breakpoint is set on `ResolveInstance` within that scope preventing
   children from starting up until StartComponentTree is called within
   that scope.

   BreakpointSystemFactory maintains a mapping from
   Option<AbsoluteMoniker> => BreakpointSystem at `ResolveInstance`
   time. When requested by the realm's root, that instance is used to
   serve the requests coming from the component.

2. Internally, BreakpointSystem holds onto an `InvocationReceiver` for
   `ResolveInstance` until StartComponentTree is called. At that time,
   the receiver is simply dropped permitting children to be started.

3. In BreakpointSystemClient, `start_component_manager` is renamed to
   `start_component_tree` and now applies to all levels.

4. `bind_single_instance` now calls `Realm::resolve_decl` to resolve the
   `ComponentDecl` because it may dispatch a `ResolveInstance` event.
   `ResolveInstance` events are expected to always be dispatched before
   `BeforeStartInstance` events.

5. Components that use the BreakpointSystem must now explicitly call
   `start_component_tree` if they expect their children to be started.

Change-Id: I86bfec7f17cce9f2928623ae3ac4d33258c405de