Add a way to kill apps without killing windows

This change allows apps to remember the app state when handling onSuspend event.

Add a new method ProcessManager::ReleaseLazyKeepaliveCountForView to decrement the lazy keepalive count without killing AppWindow.
Rename ProcessManager::IncrementLazyKeepaliveCountForView to AcquireLazyKeepaliveCountForView.
Close remaining views in CloseLazyBackgroundPageNow().

Before this change, things happen in this order:
 1. All AppWindows are destroyed
 2. Keepalive count becomes 0
 3. chrome.runtime.onSuspend is invoked
 4. The background page is unloaded.

After this change:
 1. All AppWindows have released keepalive. (by explicitly releasing it or being destroyed)
 2. Keepalive count becomes 0
 3. chrome.runtime.onSuspend is invoked
 4. Remaining AppWindows are destroyed
 5. The background page is unloaded.

BUG=416999

Review URL: https://codereview.chromium.org/689833005

Cr-Commit-Position: refs/heads/master@{#302584}

1 files changed, 13 insertions, 5 deletions

diff --git a/extensions/browser/process_manager.h b/extensions/browser/process_manager.h
index ba923d2..5dcc7f1 100644
--- a/extensions/browser/process_manager.h
+++ b/extensions/browser/process_manager.h
@@ -77,6 +77,16 @@ class ProcessManager : public KeyedService,
   // apps, not hosted apps.
   virtual content::SiteInstance* GetSiteInstanceForURL(const GURL& url);
 
+  // If the view isn't keeping the lazy background page alive, increments the
+  // keepalive count to do so.
+  void AcquireLazyKeepaliveCountForView(
+      content::RenderViewHost* render_view_host);
+
+  // If the view is keeping the lazy background page alive, decrements the
+  // keepalive count to stop doing it.
+  void ReleaseLazyKeepaliveCountForView(
+      content::RenderViewHost* render_view_host);
+
   // Unregisters a RenderViewHost as hosting any extension.
   void UnregisterRenderViewHost(content::RenderViewHost* render_view_host);
 
@@ -102,9 +112,6 @@ class ProcessManager : public KeyedService,
   void IncrementLazyKeepaliveCount(const Extension* extension);
   void DecrementLazyKeepaliveCount(const Extension* extension);
 
-  void IncrementLazyKeepaliveCountForView(
-      content::RenderViewHost* render_view_host);
-
   // Keeps a background page alive. Unlike IncrementLazyKeepaliveCount, these
   // impulses will only keep the page alive for a limited amount of time unless
   // called regularly.
@@ -210,10 +217,11 @@ class ProcessManager : public KeyedService,
 
   // Extra information we keep for each extension's background page.
   struct BackgroundPageData;
+  struct ExtensionRenderViewData;
   typedef std::string ExtensionId;
   typedef std::map<ExtensionId, BackgroundPageData> BackgroundPageDataMap;
-  typedef std::map<content::RenderViewHost*,
-      extensions::ViewType> ExtensionRenderViews;
+  typedef std::map<content::RenderViewHost*, ExtensionRenderViewData>
+      ExtensionRenderViews;
 
   // Load all background pages once the profile data is ready and the pages
   // should be loaded.