Add MemoryCoordinatorDelegate

chrome/browser/memory/tab_manager.cc

Index: chrome/browser/memory/tab_manager.cc
diff --git a/chrome/browser/memory/tab_manager.cc b/chrome/browser/memory/tab_manager.cc
index 582b2e667099f6fa0085f6721c4b9c69a37709c8..9b91aa526398a6d0b9006f23db2f4e69a7a2a264 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -211,6 +211,7 @@ void TabManager::Start() {
     }
   }
 #endif
+  MemoryCoordinatorDelegate::Set(weak_ptr_factory_.GetWeakPtr());
 }
 
 void TabManager::Stop() {
@@ -418,6 +419,17 @@ void TabManager::SetTabAutoDiscardableState(content::WebContents* contents,
   GetWebContentsData(contents)->SetAutoDiscardableState(state);
 }
 
+bool TabManager::CanSuspendRenderer(int render_process_id) {
+  auto tab_stats = GetUnsortedTabStats();
+  for (auto& tab : tab_stats) {

[bashi, 2016/10/07 04:03:41]

This isn't efficient but I couldn't figure out how to get WebContents (or ids of
WebContent) from render_process_id.

(My guess is that there are 1:N relationship between render_process_host and
web_content. Haven't looked at the implementation though)

[haraken, 2016/10/07 06:38:19]

Yeah, the underlying issue is that we have a way to suspend a renderer but don't
have a way to suspend a tab.

Once we move almost everything to per-frame schedulers, maybe we can associate
the per-frame schedulers with a tab, which will enable us to suspend tasks of a
specific tab. However, it will be an amount of work.

+    if (tab.child_process_host_id != render_process_id)
+      continue;
+    if (!CanDiscardTab(tab.tab_contents_id))

[bashi, 2016/10/07 04:03:41]

Or we may want to check only IsMediaTab()

[haraken, 2016/10/07 06:38:19]

Yes, but we can fix this later.

+      return false;
+  }
+  return true;
+}
+
 // static
 bool TabManager::CompareTabStats(const TabStats& first,
                                  const TabStats& second) {