Move all callers of GetHomeDir() to PathService::Get(base::DIR_HOME).

* Fixes GetHomeDir() for multi-profiles case on Chrome OS.
* Once user signs in on Chrome OS base::DIR_HOME is overridden with primary user homedir.
* Added content switch --homedir to pass that information to ppapi plugins since they
run in a separate process and previous base::DIR_HOME override does not apply there.

This fix doesn't require checking for --multi-profiles switch
since user_id hash is known even without it.

Note:
download_prefs.cc still uses GetHomeDir() in its DownloadPathIsDangerous() check.
// Consider downloads 'dangerous' if they go to the home directory on Linux and
// to the desktop on any platform.
In this context correct behavior is to use "real" base::GetHomeDir() and not "virtual one" base::DIR_HOME.
Since latter is remapped to some test dir in tests, in some subfolders in Chrome OS etc.

BUG=331530
TBR=vitalybuka@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270872

Review URL: https://codereview.chromium.org/200473002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272898 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 6bdc52278501985dd265048a5d14a2ba282d0717
diff --git a/base/file_util_posix.cc b/base/file_util_posix.cc
index 9270e8a..e8dec94 100644
--- a/base/file_util_posix.cc
+++ b/base/file_util_posix.cc
@@ -458,8 +458,12 @@
 #if !defined(OS_MACOSX)  // Mac implementation is in file_util_mac.mm.
 FilePath GetHomeDir() {
 #if defined(OS_CHROMEOS)
-  if (SysInfo::IsRunningOnChromeOS())
-    return FilePath("/home/chronos/user");
+  if (SysInfo::IsRunningOnChromeOS()) {
+    // On Chrome OS chrome::DIR_USER_DATA is overriden with a primary user
+    // homedir once it becomes available.
+    NOTREACHED() << "Called GetHomeDir() without base::DIR_HOME override";
+    return FilePath("/");
+  }
 #endif
 
   const char* home_dir = getenv("HOME");