memory coordinator: Add MemoryCoordinatorClient::OnPurgeMemory()

cc/resources/resource_pool.cc

Index: cc/resources/resource_pool.cc
diff --git a/cc/resources/resource_pool.cc b/cc/resources/resource_pool.cc
index 61a7ae3f9fdc6519376a1b473631a73bc7cd3d40..c2003758c4ba65ef0348e1988699c79f41dfb1b6 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -480,23 +480,9 @@ bool ResourcePool::OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
   return true;
 }
 
-void ResourcePool::OnMemoryStateChange(base::MemoryState state) {
-  switch (state) {
-    case base::MemoryState::NORMAL:
-      // TODO(tasak): go back to normal state.
-      break;
-    case base::MemoryState::THROTTLED:
-      // TODO(tasak): make the limits of this component's caches smaller to
-      // save memory usage.
-      break;
-    case base::MemoryState::SUSPENDED:
-      // Release all resources, regardless of how recently they were used.
-      EvictResourcesNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
-      break;
-    case base::MemoryState::UNKNOWN:
-      // NOT_REACHED.
-      break;
-  }
+void ResourcePool::OnPurgeMemory() {
+  // Release all resources, regardless of how recently they were used.
+  EvictResourcesNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
 }
 
 }  // namespace cc