Modify PurgeAndSuspend to see WebContents

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..0c2791c84d987e96ca53789920c1d43b95e58170 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -670,6 +670,23 @@ void TabManager::UpdateTimerCallback() {
   PurgeAndSuspendBackgroundedTabs();
 }
 
+bool TabManager::CanPurgeAndSuspendBackgroundedTab(
+    int64_t target_web_contents_id) const {
+  TabStripModel* model;
+  int idx = FindTabStripModelById(target_web_contents_id, &model);
+  if (idx == -1)
+    return false;
+
+  WebContents* web_contents = model->GetWebContentsAt(idx);
+
+  // Do not suspend tabs that are playing either playing audio or accessing the
+  // microphone or camera as it's too distruptive to the user experience.
+  if (IsMediaTab(web_contents))
+    return false;
+
+  return true;
+}
+
 void TabManager::PurgeAndSuspendBackgroundedTabs() {

[chrisha, 2016/10/06 13:24:30]

I didn't realize this had been implemented in TabManager. The plan with MC is to
move all the throttle/suspend/discard logic to MC, so I'm curious why this ended
up here? Temporarily while MCv0 is being worked on by bashi?

[tasak, 2016/10/07 05:48:42]

I agree with you. The logic should be implemented in MC.
Since I don't want to disturb MCv0 work, temporarily I'm trying to implement the
logic in tab_manager.

Now bashi@ has just created a patch to move the logic to MC:
https://codereview.chromium.org/2399293002/

I'm ok to wait until bashi@'s patch is landed.

   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
@@ -695,6 +712,8 @@ void TabManager::PurgeAndSuspendBackgroundedTabs() {
     // timers if we want necessary and sufficient signals.
     if (tab.last_active > purge_and_suspend_time_threshold)
       continue;
+    if (!CanPurgeAndSuspendBackgroundedTab(tab.tab_contents_id))
+      continue;
     tab.render_process_host->PurgeAndSuspend();
   }
 }