Keep NaCl plugins used in app background pages alive when active.

Activity in Native Client plugins results in IPC messages
sent to the BrowserPpapiHostImpl and routed to call
extensions::ProcessManager::KeepaliveImpulse.

Implementation patch, to be followed by tests. See:
https://codereview.chromium.org/111563006/ Tests.
https://codereview.chromium.org/105873003/ Cumulative patch.

Design doc: 
https://docs.google.com/a/chromium.org/document/d/1mI0lS1rfAf-BAGLmWAEcWy37Xq9dOvgfMx8OqeUMXts/edit#

BUG=298339

Review URL: https://codereview.chromium.org/61063003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241702 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 83 insertions, 2 deletions

diff --git a/ppapi/proxy/plugin_globals.cc b/ppapi/proxy/plugin_globals.cc
index 59b5191..d34adf1 100644
--- a/ppapi/proxy/plugin_globals.cc
+++ b/ppapi/proxy/plugin_globals.cc
@@ -10,11 +10,18 @@
 #include "ipc/ipc_sender.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
 #include "ppapi/proxy/plugin_proxy_delegate.h"
+#include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/ppb_message_loop_proxy.h"
 #include "ppapi/proxy/resource_reply_thread_registrar.h"
 #include "ppapi/shared_impl/proxy_lock.h"
 #include "ppapi/thunk/enter.h"
 
+namespace {
+
+const int kKeepaliveThrottleIntervalDefault = 5000;
+
+}  // namespace
+
 namespace ppapi {
 namespace proxy {
 
@@ -54,7 +61,11 @@ PluginGlobals::PluginGlobals()
       plugin_proxy_delegate_(NULL),
       callback_tracker_(new CallbackTracker),
       resource_reply_thread_registrar_(
-          new ResourceReplyThreadRegistrar(GetMainThreadMessageLoop())) {
+          new ResourceReplyThreadRegistrar(GetMainThreadMessageLoop())),
+      plugin_recently_active_(false),
+      keepalive_throttle_interval_milliseconds_(
+          kKeepaliveThrottleIntervalDefault),
+      weak_factory_(this) {
   DCHECK(!plugin_globals_);
   plugin_globals_ = this;
 
@@ -71,7 +82,11 @@ PluginGlobals::PluginGlobals(PerThreadForTest per_thread_for_test)
       plugin_proxy_delegate_(NULL),
       callback_tracker_(new CallbackTracker),
       resource_reply_thread_registrar_(
-          new ResourceReplyThreadRegistrar(GetMainThreadMessageLoop())) {
+          new ResourceReplyThreadRegistrar(GetMainThreadMessageLoop())),
+      plugin_recently_active_(false),
+      keepalive_throttle_interval_milliseconds_(
+          kKeepaliveThrottleIntervalDefault),
+      weak_factory_(this) {
   DCHECK(!plugin_globals_);
 }
 
@@ -165,6 +180,21 @@ base::TaskRunner* PluginGlobals::GetFileTaskRunner() {
   return file_thread_->message_loop_proxy();
 }
 
+void PluginGlobals::MarkPluginIsActive() {
+  if (!plugin_recently_active_) {
+    plugin_recently_active_ = true;
+    if (!GetBrowserSender() || !base::MessageLoop::current())
+      return;
+    GetBrowserSender()->Send(new PpapiHostMsg_Keepalive());
+
+    GetMainThreadMessageLoop()->PostDelayedTask(FROM_HERE,
+        RunWhileLocked(base::Bind(&PluginGlobals::OnReleaseKeepaliveThrottle,
+                                  weak_factory_.GetWeakPtr())),
+        base::TimeDelta::FromMilliseconds(
+            keepalive_throttle_interval_milliseconds()));
+  }
+}
+
 IPC::Sender* PluginGlobals::GetBrowserSender() {
   if (!browser_sender_.get()) {
     browser_sender_.reset(
@@ -195,9 +225,22 @@ MessageLoopResource* PluginGlobals::loop_for_main_thread() {
   return loop_for_main_thread_.get();
 }
 
+int PluginGlobals::keepalive_throttle_interval_milliseconds() const {
+  return keepalive_throttle_interval_milliseconds_;
+}
+
+void PluginGlobals::set_keepalive_throttle_interval_milliseconds(int i) {
+  keepalive_throttle_interval_milliseconds_ = i;
+}
+
 bool PluginGlobals::IsPluginGlobals() const {
   return true;
 }
 
+void PluginGlobals::OnReleaseKeepaliveThrottle() {
+  ppapi::ProxyLock::AssertAcquiredDebugOnly();
+  plugin_recently_active_ = false;
+}
+
 }  // namespace proxy
 }  // namespace ppapi
diff --git a/ppapi/proxy/plugin_globals.h b/ppapi/proxy/plugin_globals.h
index 029e2d2..dac33b6 100644
--- a/ppapi/proxy/plugin_globals.h
+++ b/ppapi/proxy/plugin_globals.h
@@ -74,6 +74,7 @@ class PPAPI_PROXY_EXPORT PluginGlobals : public PpapiGlobals {
                                       const std::string& value) OVERRIDE;
   virtual MessageLoopShared* GetCurrentMessageLoop() OVERRIDE;
   base::TaskRunner* GetFileTaskRunner() OVERRIDE;
+  virtual void MarkPluginIsActive() OVERRIDE;
 
   // Returns the channel for sending to the browser.
   IPC::Sender* GetBrowserSender();
@@ -133,12 +134,21 @@ class PPAPI_PROXY_EXPORT PluginGlobals : public PpapiGlobals {
     return resource_reply_thread_registrar_.get();
   }
 
+  // Interval to limit how many IPC messages are sent indicating that the plugin
+  // is active and should be kept alive. The value must be smaller than any
+  // threshold used to kill inactive plugins by the embedder host.
+  int keepalive_throttle_interval_milliseconds() const;
+  void set_keepalive_throttle_interval_milliseconds(int i);
+
  private:
   class BrowserSender;
 
   // PpapiGlobals overrides.
   virtual bool IsPluginGlobals() const OVERRIDE;
 
+  // Locks the proxy lock and releases the throttle on keepalive IPC messages.
+  void OnReleaseKeepaliveThrottle();
+
   static PluginGlobals* plugin_globals_;
 
   PluginProxyDelegate* plugin_proxy_delegate_;
@@ -167,6 +177,17 @@ class PPAPI_PROXY_EXPORT PluginGlobals : public PpapiGlobals {
 
   scoped_refptr<ResourceReplyThreadRegistrar> resource_reply_thread_registrar_;
 
+  // Indicates activity by the plugin. Used to monitor when a plugin can be
+  // shutdown due to idleness. Current needs do not require differentiating
+  // between idle state between multiple instances, if any are active they are
+  // all considered active.
+  bool plugin_recently_active_;
+
+  int keepalive_throttle_interval_milliseconds_;
+
+  // Member variables should appear before the WeakPtrFactory, see weak_ptr.h.
+  base::WeakPtrFactory<PluginGlobals> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(PluginGlobals);
 };
 
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index 4b4fed8..086d42a 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -726,6 +726,9 @@ IPC_MESSAGE_ROUTED2(PpapiMsg_PPPVideoDecoder_NotifyError,
                     PP_VideoDecodeError_Dev /* error */)
 #endif  // !defined(OS_NACL) && !defined(NACL_WIN64)
 
+// Reports to the browser that a plugin has been active.
+IPC_MESSAGE_CONTROL0(PpapiHostMsg_Keepalive)
+
 // -----------------------------------------------------------------------------
 // These are from the plugin to the renderer.
 
diff --git a/ppapi/shared_impl/ppapi_globals.cc b/ppapi/shared_impl/ppapi_globals.cc
index 28ed2cf..f652f15 100644
--- a/ppapi/shared_impl/ppapi_globals.cc
+++ b/ppapi/shared_impl/ppapi_globals.cc
@@ -69,6 +69,9 @@ bool PpapiGlobals::IsPluginGlobals() const {
   return false;
 }
 
+void PpapiGlobals::MarkPluginIsActive() {
+}
+
 // static
 PpapiGlobals* PpapiGlobals::GetThreadLocalPointer() {
   return tls_ppapi_globals_for_test.Pointer()->Get();
diff --git a/ppapi/shared_impl/ppapi_globals.h b/ppapi/shared_impl/ppapi_globals.h
index 93ab299..d9be0387 100644
--- a/ppapi/shared_impl/ppapi_globals.h
+++ b/ppapi/shared_impl/ppapi_globals.h
@@ -128,6 +128,12 @@ class PPAPI_SHARED_EXPORT PpapiGlobals {
   virtual bool IsHostGlobals() const;
   virtual bool IsPluginGlobals() const;
 
+  // Records that the plugin is active. The plugin reports that it is active to
+  // containers that monitor and shutdown idle content such as background apps.
+  // This method only has an effect on the plugin process, calls from the
+  // renderer process will have no effect.
+  virtual void MarkPluginIsActive();
+
  private:
   // Return the thread-local pointer which is used only for unit testing. It
   // should always be NULL when running in production. It allows separate
diff --git a/ppapi/thunk/enter.cc b/ppapi/thunk/enter.cc
index 47889dd..2adc7f2 100644
--- a/ppapi/thunk/enter.cc
+++ b/ppapi/thunk/enter.cc
@@ -32,16 +32,19 @@ namespace subtle {
 EnterBase::EnterBase()
     : resource_(NULL),
       retval_(PP_OK) {
+  PpapiGlobals::Get()->MarkPluginIsActive();
 }
 
 EnterBase::EnterBase(PP_Resource resource)
     : resource_(GetResource(resource)),
       retval_(PP_OK) {
+  PpapiGlobals::Get()->MarkPluginIsActive();
 }
 
 EnterBase::EnterBase(PP_Instance instance, SingletonResourceID resource_id)
     : resource_(GetSingletonResource(instance, resource_id)),
       retval_(PP_OK) {
+  PpapiGlobals::Get()->MarkPluginIsActive();
 }
 
 EnterBase::EnterBase(PP_Resource resource,
@@ -49,6 +52,7 @@ EnterBase::EnterBase(PP_Resource resource,
     : resource_(GetResource(resource)),
       retval_(PP_OK) {
   callback_ = new TrackedCallback(resource_, callback);
+  PpapiGlobals::Get()->MarkPluginIsActive();
 }
 
 EnterBase::EnterBase(PP_Instance instance, SingletonResourceID resource_id,
@@ -59,6 +63,7 @@ EnterBase::EnterBase(PP_Instance instance, SingletonResourceID resource_id,
   if (!resource_)
     retval_ = PP_ERROR_BADARGUMENT;
   callback_ = new TrackedCallback(resource_, callback);
+  PpapiGlobals::Get()->MarkPluginIsActive();
 }
 
 EnterBase::~EnterBase() {