Refactor ProcessSingleton to allow a Desktop process to activate Metro Chrome...

Refactor ProcessSingleton to allow a Desktop process to activate Metro Chrome instead of grabbing the singleton (while making sure it simply RDVs if there already is an existing Chrome).

Use a Windows event to let the Metro process notify the Desktop process once it grabbed the singleton (no more Sleep()).

The idea is the following:

0) Any process always tries to rendez-vous before anything else.
1) A Metro process can always try to grab the singleton.
2) A Desktop process might wait if:
  a) The metro activation event exists
  b) The metro activation event doesn't exist, but ShouldActivate() returns true
    - In which case it creates the metro activation event and activates Metro Chrome (which will notify this process via the event once it grabbed the singleton; at which point this process should rendez-vous with it).

All of this is done while holding a global mutex (only releasing it while waiting and re-acquiring it before continuing when notified).

The process singleton acquiring logic has also been moved from the constructor to Create().

BUG=155585, 159869
TEST=Process singleton works as before (and better in tricky corner cases -- see http://crbug.com/159869) on Win8.

Review URL: https://chromiumcodereview.appspot.com/11099053

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171105 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/process_singleton.h

@@ -24,16 +24,11 @@
 #include "base/threading/non_thread_safe.h"
 #include "ui/gfx/native_widget_types.h"
 
-#if defined(OS_POSIX)
-#include "base/file_path.h"
-#endif  // defined(OS_POSIX)
-
 #if defined(OS_LINUX) || defined(OS_OPENBSD)
 #include "base/files/scoped_temp_dir.h"
 #endif  // defined(OS_LINUX) || defined(OS_OPENBSD)
 
 class CommandLine;
-class FilePath;
 
 // ProcessSingleton ----------------------------------------------------------
 //
@@ -70,7 +65,11 @@ class ProcessSingleton : public base::NonThreadSafe {
   // Notify another process, if available. Otherwise sets ourselves as the
   // singleton instance and stores the provided callback for notification from
   // future processes. Returns PROCESS_NONE if we became the singleton
-  // instance.
+  // instance. Callers are guaranteed to either have notified an existing
+  // process or have grabbed the singleton (unless the profile is locked by an
+  // unreachable process).
+  // TODO(brettw): Make the implementation of this method non-platform-specific
+  // by making Linux re-use the Windows implementation.
   NotifyResult NotifyOtherProcessOrCreate(
       const NotificationCallback& notification_callback);
 
@@ -120,13 +119,9 @@ class ProcessSingleton : public base::NonThreadSafe {
 
  protected:
   // Notify another process, if available.
-  // Returns true if another process was found and notified, false if we
-  // should continue with this process.
-  // Windows code roughly based on Mozilla.
-  //
-  // TODO(brettw): this will not handle all cases. If two processes start up too
-  // close to each other, the Create() might not yet have happened for the
-  // first one, so this function won't find it.
+  // Returns true if another process was found and notified, false if we should
+  // continue with the current process.
+  // On Windows, Create() has to be called before this.
   NotifyResult NotifyOtherProcess();
 
 #if defined(OS_LINUX) || defined(OS_OPENBSD)
@@ -167,6 +162,7 @@ class ProcessSingleton : public base::NonThreadSafe {
   HWND window_;  // The HWND_MESSAGE window.
   bool is_virtualized_;  // Stuck inside Microsoft Softricity VM environment.
   HANDLE lock_file_;
+  FilePath user_data_dir_;
 #elif defined(OS_LINUX) || defined(OS_OPENBSD)
   // Return true if the given pid is one of our child processes.
   // Assumes that the current pid is the root of all pids of the current