Add comment explaining why chrome_proxy.exe exists

Bug: 732357
Change-Id: Iedae967997bade3143ba6a2b8bd8e5fb43534ca2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1585399
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Bugs Nash <bugsnash@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654322}
diff --git a/chrome/chrome_proxy/chrome_proxy_main_win.cc b/chrome/chrome_proxy/chrome_proxy_main_win.cc
index 2f0ac83..4ae74b0 100644
--- a/chrome/chrome_proxy/chrome_proxy_main_win.cc
+++ b/chrome/chrome_proxy/chrome_proxy_main_win.cc
@@ -20,6 +20,20 @@
 
 }  // namespace
 
+// This binary is a workaround for Windows 10 start menu pinning icon bug:
+// https://crbug.com/732357.
+//
+// When a shortcut is pinned in the Windows 10 start menu Windows will follow
+// the shortcut, find the target executable, look for a <target>.manifest file
+// in the same directory and use the icon specified in there for the start menu
+// pin. Because bookmark app shortcuts are shortcuts to Chrome (plus a few
+// command line parameters) Windows ends up using the Chrome icon specified in
+// chrome.exe.manifest instead of the site's icon stored inside the shortcut.
+//
+// The chrome_proxy.exe binary workaround "fixes" this by having bookmark app
+// shortcuts target chrome_proxy.exe instead of chrome.exe such that Windows
+// won't find a manifest and falls back to using the shortcut's icons as
+// originally intended.
 int WINAPI wWinMain(HINSTANCE instance,
                     HINSTANCE prev_instance,
                     wchar_t* /*command_line*/,