Sequentialize calls to PluginList::GetPlugins from PluginService.

BUG=105987
TEST=none


Review URL: https://chromiumcodereview.appspot.com/10381087

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137396 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 30 insertions, 18 deletions

diff --git a/webkit/plugins/npapi/plugin_list.cc b/webkit/plugins/npapi/plugin_list.cc
index 0b04b31..6023fee 100644
--- a/webkit/plugins/npapi/plugin_list.cc
+++ b/webkit/plugins/npapi/plugin_list.cc
@@ -232,7 +232,7 @@ bool PluginList::DebugPluginLoading() {
 
 void PluginList::RefreshPlugins() {
   base::AutoLock lock(lock_);
-  plugins_need_refresh_ = true;
+  loading_state_ = LOADING_STATE_NEEDS_REFRESH;
 }
 
 void PluginList::AddExtraPluginPath(const FilePath& plugin_path) {
@@ -371,7 +371,7 @@ bool PluginList::ParseMimeTypes(
 }
 
 PluginList::PluginList()
-    : plugins_need_refresh_(true) {
+    : loading_state_(LOADING_STATE_NEEDS_REFRESH) {
   PlatformInit();
   AddHardcodedPluginGroups(kGroupDefinitions,
                            ARRAYSIZE_UNSAFE(kGroupDefinitions));
@@ -379,7 +379,7 @@ PluginList::PluginList()
 
 PluginList::PluginList(const PluginGroupDefinition* definitions,
                        size_t num_definitions)
-    : plugins_need_refresh_(true) {
+    : loading_state_(LOADING_STATE_NEEDS_REFRESH) {
   // Don't do platform-dependend initialization in unit tests.
   AddHardcodedPluginGroups(definitions, num_definitions);
 }
@@ -398,12 +398,8 @@ void PluginList::LoadPluginsInternal(ScopedVector<PluginGroup>* plugin_groups) {
   base::Closure will_load_callback;
   {
     base::AutoLock lock(lock_);
-    // Clear the refresh bit now, because it might get set again before we
-    // reach the end of the method.
-    plugins_need_refresh_ = false;
     will_load_callback = will_load_plugins_callback_;
   }
-
   if (!will_load_callback.is_null())
     will_load_callback.Run();
 
@@ -421,8 +417,10 @@ void PluginList::LoadPluginsInternal(ScopedVector<PluginGroup>* plugin_groups) {
 void PluginList::LoadPlugins() {
   {
     base::AutoLock lock(lock_);
-    if (!plugins_need_refresh_)
+    if (loading_state_ == LOADING_STATE_UP_TO_DATE)
       return;
+
+    loading_state_ = LOADING_STATE_REFRESHING;
   }
 
   ScopedVector<PluginGroup> new_plugin_groups;
@@ -431,6 +429,10 @@ void PluginList::LoadPlugins() {
 
   base::AutoLock lock(lock_);
   plugin_groups_.swap(new_plugin_groups);
+  // If we haven't been invalidated in the mean time, mark the plug-in list as
+  // up-to-date.
+  if (loading_state_ != LOADING_STATE_NEEDS_REFRESH)
+    loading_state_ = LOADING_STATE_UP_TO_DATE;
 }
 
 bool PluginList::LoadPlugin(const FilePath& path,
@@ -504,7 +506,8 @@ const std::vector<PluginGroup*>& PluginList::GetHardcodedPluginGroups() const {
 void PluginList::SetPlugins(const std::vector<webkit::WebPluginInfo>& plugins) {
   base::AutoLock lock(lock_);
 
-  plugins_need_refresh_ = false;
+  DCHECK_NE(LOADING_STATE_REFRESHING, loading_state_);
+  loading_state_ = LOADING_STATE_UP_TO_DATE;
 
   plugin_groups_.reset();
   for (std::vector<webkit::WebPluginInfo>::const_iterator it = plugins.begin();
@@ -532,7 +535,7 @@ void PluginList::GetPlugins(std::vector<WebPluginInfo>* plugins) {
 bool PluginList::GetPluginsIfNoRefreshNeeded(
     std::vector<webkit::WebPluginInfo>* plugins) {
   base::AutoLock lock(lock_);
-  if (plugins_need_refresh_)
+  if (loading_state_ != LOADING_STATE_UP_TO_DATE)
     return false;
 
   for (size_t i = 0; i < plugin_groups_.size(); ++i) {
@@ -557,7 +560,7 @@ void PluginList::GetPluginInfoArray(
     LoadPlugins();
   base::AutoLock lock(lock_);
   if (use_stale)
-    *use_stale = plugins_need_refresh_;
+    *use_stale = (loading_state_ != LOADING_STATE_UP_TO_DATE);
   info->clear();
   if (actual_mime_types)
     actual_mime_types->clear();
diff --git a/webkit/plugins/npapi/plugin_list.h b/webkit/plugins/npapi/plugin_list.h
index d01b38f..a948782 100644
--- a/webkit/plugins/npapi/plugin_list.h
+++ b/webkit/plugins/npapi/plugin_list.h
@@ -121,7 +121,7 @@ class WEBKIT_PLUGINS_EXPORT PluginList {
       const string16& mime_type_descriptions,
       std::vector<webkit::WebPluginMimeType>* parsed_mime_types);
 
-  // Get all the plugins synchronously.
+  // Get all the plugins synchronously, loading them if necessary.
   void GetPlugins(std::vector<webkit::WebPluginInfo>* plugins);
 
   // Returns true if the list of plugins is cached and is copied into the out
@@ -195,6 +195,17 @@ class WEBKIT_PLUGINS_EXPORT PluginList {
                                  ScopedVector<PluginGroup>* plugin_groups);
 
  private:
+  enum LoadingState {
+    LOADING_STATE_NEEDS_REFRESH,
+    LOADING_STATE_REFRESHING,
+    LOADING_STATE_UP_TO_DATE,
+  };
+
+  struct InternalPlugin {
+    webkit::WebPluginInfo info;
+    PluginEntryPoints entry_points;
+  };
+
   friend class PluginListTest;
   friend struct base::DefaultLazyInstanceTraits<PluginList>;
   FRIEND_TEST_ALL_PREFIXES(PluginGroupTest, PluginGroupDefinition);
@@ -268,8 +279,10 @@ class WEBKIT_PLUGINS_EXPORT PluginList {
   // Internals
   //
 
-  // If true, we reload plugins even if they've been loaded already.
-  bool plugins_need_refresh_;
+  // States whether we will load the plug-in list the next time we try to access
+  // it, whether we are currently in the process of loading it, or whether we
+  // consider it up-to-date.
+  LoadingState loading_state_;
 
   // Extra plugin paths that we want to search when loading.
   std::vector<FilePath> extra_plugin_paths_;
@@ -277,10 +290,6 @@ class WEBKIT_PLUGINS_EXPORT PluginList {
   // Extra plugin directories that we want to search when loading.
   std::vector<FilePath> extra_plugin_dirs_;
 
-  struct InternalPlugin {
-    webkit::WebPluginInfo info;
-    PluginEntryPoints entry_points;
-  };
   // Holds information about internal plugins.
   std::vector<InternalPlugin> internal_plugins_;