Commit History transaction when app is backgrounded on iOS

Request time from the OS when the application is backgrounded on iOS to
try to commit all pending history transactions.

BUG=429756

Review URL: https://codereview.chromium.org/1015153002

Cr-Commit-Position: refs/heads/master@{#321329}

components/history/core/browser/history_backend.cc

@@ -44,6 +44,10 @@
 #include "url/gurl.h"
 #include "url/url_constants.h"
 
+#if defined(OS_IOS)
+#include "base/ios/scoped_critical_action.h"
+#endif
+
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
@@ -260,6 +264,12 @@ void HistoryBackend::Closing() {
   delegate_.reset();
 }
 
+#if defined(OS_IOS)
+void HistoryBackend::PersistState() {
+  Commit();
+}
+#endif
+
 void HistoryBackend::ClearCachedDataForContextID(ContextID context_id) {
   tracker_.ClearCachedDataForContextID(context_id);
 }
@@ -2168,6 +2178,12 @@ void HistoryBackend::Commit() {
   if (!db_)
     return;
 
+#if defined(OS_IOS)
+  // Attempts to get the application running long enough to commit the database
+  // transaction if it is currently being backgrounded.
+  base::ios::ScopedCriticalAction scoped_critical_action;
+#endif
+
   // Note that a commit may not actually have been scheduled if a caller
   // explicitly calls this instead of using ScheduleCommit. Likewise, we
   // may reset the flag written by a pending commit. But this is OK! It

components/history/core/browser/history_backend.h

@@ -191,6 +191,12 @@ class HistoryBackend : public base::RefCountedThreadSafe<HistoryBackend>,
   // actually be deleted.
   void Closing();
 
+#if defined(OS_IOS)
+  // Persists any in-flight state, without actually shutting down the history
+  // system. This is intended for use when the application is backgrounded.
+  void PersistState();
+#endif
+
   void ClearCachedDataForContextID(ContextID context_id);
 
   // Navigation ----------------------------------------------------------------

components/history/core/browser/history_service.cc

@@ -46,6 +46,10 @@
 #include "sync/api/sync_error_factory.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
+#if defined(OS_IOS)
+#include "base/critical_closure.h"
+#endif
+
 using base::Time;
 
 namespace history {
@@ -205,6 +209,17 @@ bool HistoryService::BackendLoaded() {
   return backend_loaded_;
 }
 
+#if defined(OS_IOS)
+void HistoryService::HandleBackgrounding() {
+  if (!thread_ || !history_backend_.get())
+    return;
+
+  ScheduleTask(PRIORITY_NORMAL,
+               base::MakeCriticalClosure(base::Bind(
+                   &HistoryBackend::PersistState, history_backend_.get())));
+}
+#endif
+
 void HistoryService::ClearCachedDataForContextID(ContextID context_id) {
   DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());

components/history/core/browser/history_service.h

@@ -105,6 +105,12 @@ class HistoryService : public syncer::SyncableService, public KeyedService {
   // Returns true if the backend has finished loading.
   bool backend_loaded() const { return backend_loaded_; }
 
+#if defined(OS_IOS)
+  // Causes the history backend to commit any in-progress transactions. Called
+  // when the application is being backgrounded.
+  void HandleBackgrounding();
+#endif
+
   // Context ids are used to scope page IDs (see AddPage). These contexts
   // must tell us when they are being invalidated so that we can clear
   // out any cached data associated with that context.