Add a PrefRegistrationFlags::LOSSY_PREF flag for writing lossy prefs

This adds a registration flag for marking a pref as "lossy". There is no strict
time guarantee on when a lossy pref will be persisted to permanent storage when
it is modified.

WriteablePrefStore::PrefWriteFlags are introduced to be used to change the way
that prefs get written into a WriteablePrefStore.

The plumbing to pass registration flags down from PrefService into the
WriteablePrefStore and convert them into PrefWriteFlags is also added here.
The code which actually makes the pref behave in a lossy way has not been
added yet.

BUG=476800

Review URL: https://codereview.chromium.org/1092223004

Cr-Commit-Position: refs/heads/master@{#328481}

1 files changed, 8 insertions, 5 deletions

diff --git a/chrome/service/service_process_prefs.cc b/chrome/service/service_process_prefs.cc
index d923185..7f43943 100644
--- a/chrome/service/service_process_prefs.cc
+++ b/chrome/service/service_process_prefs.cc
@@ -39,7 +39,8 @@ std::string ServiceProcessPrefs::GetString(
 
 void ServiceProcessPrefs::SetString(const std::string& key,
                                     const std::string& value) {
-  prefs_->SetValue(key, new base::StringValue(value));
+  prefs_->SetValue(key, new base::StringValue(value),
+                   WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 }
 
 bool ServiceProcessPrefs::GetBoolean(const std::string& key,
@@ -53,7 +54,8 @@ bool ServiceProcessPrefs::GetBoolean(const std::string& key,
 }
 
 void ServiceProcessPrefs::SetBoolean(const std::string& key, bool value) {
-  prefs_->SetValue(key, new base::FundamentalValue(value));
+  prefs_->SetValue(key, new base::FundamentalValue(value),
+                   WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 }
 
 int ServiceProcessPrefs::GetInt(const std::string& key,
@@ -67,7 +69,8 @@ int ServiceProcessPrefs::GetInt(const std::string& key,
 }
 
 void ServiceProcessPrefs::SetInt(const std::string& key, int value) {
-  prefs_->SetValue(key, new base::FundamentalValue(value));
+  prefs_->SetValue(key, new base::FundamentalValue(value),
+                   WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 }
 
 const base::DictionaryValue* ServiceProcessPrefs::GetDictionary(
@@ -91,10 +94,10 @@ const base::ListValue* ServiceProcessPrefs::GetList(
 }
 
 void ServiceProcessPrefs::SetValue(const std::string& key, base::Value* value) {
-  prefs_->SetValue(key, value);
+  prefs_->SetValue(key, value, WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 }
 
 void ServiceProcessPrefs::RemovePref(const std::string& key) {
-  prefs_->RemoveValue(key);
+  prefs_->RemoveValue(key, WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS);
 }