Put app shim IPC socket in a temporary directory. (Mac)

chrome/common/mac/app_mode_common.mm

Index: chrome/common/mac/app_mode_common.mm
diff --git a/chrome/common/mac/app_mode_common.mm b/chrome/common/mac/app_mode_common.mm
index 317dec3b6331e32aa8ae332f02d4c4d9b74708f8..e0333ef2630905870e4d57817f8c97021c86c7ba 100644
--- a/chrome/common/mac/app_mode_common.mm
+++ b/chrome/common/mac/app_mode_common.mm
@@ -4,6 +4,10 @@
 
 #include "chrome/common/mac/app_mode_common.h"
 
+#include "base/base64.h"
+#include "base/sha1.h"
+#include "base/strings/string_util.h"
+
 namespace app_mode {
 
 const char kAppShimSocketName[] = "App Shim Socket";
@@ -40,4 +44,15 @@ ChromeAppModeInfo::ChromeAppModeInfo()
 ChromeAppModeInfo::~ChromeAppModeInfo() {
 }
 
+base::FilePath GetShortSocketPath(const base::FilePath& full_path) {
+  std::string short_path;
+  if (base::Base64Encode(base::SHA1HashString(full_path.value()),

[tapted, 2013/11/21 11:12:05]

under what cases can it return false?

I got curious and answered it myself... modp_b64_encode never returns
MODP_B64_ERROR so the check in Base64Encode is pointless, and base::Base64Encode
should really return `void`.

I guess maybe NOTREACHED() before the final return?

[jackhou1, 2013/11/22 00:20:40]

Done.

+                         &short_path)) {
+    ReplaceChars(short_path, "/", "_", &short_path);

[tapted, 2013/11/21 11:12:05]

I think short_path will have a guaranteed length - maybe DCHECK_EQ?

[jackhou1, 2013/11/22 00:20:40]

Done.

+    return base::FilePath("/tmp").Append(short_path);
+  }
+
+  return base::FilePath();
+}
+
 }  // namespace app_mode