Remove all but one use of WeakPtrFactory::DetachFromThread.

This CL changes WeakPtr in the following ways:
* Changes thread-bindings semantics so that WeakPtrs only become bound when the first one is dereferenced, or the owning factory invalidates them.
* Removes WeakPtrFactory::DetachFromThread.
* Renames SupportsWeakPtr::DetachFromThread  to DetachFromThreadHack.

Calling code changes to allow this:
* Unnecessary DetachFromThread() calls removed from PluginInfoMessageFilter, DhcpProxyScript[Adapter]FetcherWin and (Chromoting's) PolicyWatcherLinux.
* DetachFromThread() calls rendered unnecessary by change in binding semantics removed from IOThread, SearchProviderInstallData, RuleRegistryWithCache and GLSurfaceGlx.

WebGraphicsContext3DInProcessCommandBufferImpl uses the re-named DetachFromThreadHack() - bug 234964 tracks work to remove that use.

BUG=232143, 234964

Review URL: https://chromiumcodereview.appspot.com/14299011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@202038 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 7 deletions

diff --git a/remoting/host/policy_hack/policy_watcher_linux.cc b/remoting/host/policy_hack/policy_watcher_linux.cc
index 641af9c..f3cffea 100644
--- a/remoting/host/policy_hack/policy_watcher_linux.cc
+++ b/remoting/host/policy_hack/policy_watcher_linux.cc
@@ -51,12 +51,6 @@ class PolicyWatcherLinux : public PolicyWatcher {
       : PolicyWatcher(task_runner),
         config_dir_(config_dir),
         weak_factory_(this) {
-    // Detach the factory because we ensure that only the policy thread ever
-    // calls methods on this. Also, the API contract of having to call
-    // StopWatching() (which signals completion) after StartWatching()
-    // before this object can be destructed ensures there are no users of
-    // this object before it is destructed.
-    weak_factory_.DetachFromThread();
   }
 
   virtual ~PolicyWatcherLinux() {}
@@ -84,8 +78,12 @@ class PolicyWatcherLinux : public PolicyWatcher {
 
   virtual void StopWatchingInternal() OVERRIDE {
     DCHECK(OnPolicyWatcherThread());
-    // Cancel any inflight requests.
+
+    // Stop watching for changes to files in the policies directory.
     watcher_.reset();
+
+    // Orphan any pending OnFilePathChanged tasks.
+    weak_factory_.InvalidateWeakPtrs();
   }
 
  private: