Add resource_coordinator::TabLifecycleUnit (impl).

TabLifecycleUnit represents a tab and implements the LifecycleUnit
and TabLifecycleUnitExternal interfaces.

For now, most important methods are not implemented.

Bug: 775644
Change-Id: Ib30285e69af6e35c767d5f4336633c72ab02d32d
Reviewed-on: https://chromium-review.googlesource.com/788336
Reviewed-by: Chris Hamilton <[email protected]>
Commit-Queue: François Doray <[email protected]>
Cr-Commit-Position: refs/heads/master@{#522554}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index c5c4676..ad182e5 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -2565,6 +2565,8 @@
       "resource_coordinator/lifecycle_unit_source_base.h",
       "resource_coordinator/lifecycle_unit_source_observer.h",
       "resource_coordinator/tab_lifecycle_observer.h",
+      "resource_coordinator/tab_lifecycle_unit.cc",
+      "resource_coordinator/tab_lifecycle_unit.h",
       "resource_coordinator/tab_lifecycle_unit_external.cc",
       "resource_coordinator/tab_lifecycle_unit_external.h",
       "resource_coordinator/tab_manager.cc",