Revert "Refactored IPH demo mode to be run cross-platform."

This reverts commit 31093e7189d7a055b362bc8f325ef96099ee1b20.

Reason for revert: This change adds static initializers to the build, which is not allowed. It broke the `sizes` step as a result:

https://luci-milo.appspot.com/buildbot/chromium/Linux%20x64/41189
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Fchromium%2FLinux_x64%2F41189%2F%2B%2Frecipes%2Fsteps%2Fsizes%2F0%2Fstdout

Original change's description:
> Refactored IPH demo mode to be run cross-platform.
> 
> Current code only enables IPH demo mode on Android, restricting testing
> on other platforms.
> 
> This feature needs to be cross-platform to be used with deferred onboarding
> (new tab) on Desktop Chrome.
> 
> Things that were changed in this CL:
> * Makes the whole feature engagement tracker available to all platforms
> * Updated documentation to reflect this change
> * Enables demo mode in chrome://flags to be cross-platform
> * Change in feature_engagement_tracker_impl.cc was necessary to make it
>   work for Windows' pathnames.
> 
> Bug: 729138
> Change-Id: I76b382e004ea9b73bd7fb2df26aa83ff7856422e
> Reviewed-on: https://chromium-review.googlesource.com/518933
> Commit-Queue: Catherine Chung <[email protected]>
> Reviewed-by: Tommy Nyquist <[email protected]>
> Reviewed-by: Scott Violet <[email protected]>
> Reviewed-by: Robert Liao <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#477045}

[email protected],[email protected],[email protected],[email protected],[email protected]
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=729138

Change-Id: Ia6b18d2b797eacea75ec16349f9f42d32ea3f0e8
Reviewed-on: https://chromium-review.googlesource.com/524289
Commit-Queue: Dirk Pranke <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Cr-Commit-Position: refs/heads/master@{#477106}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 054f5e6b..db5fad8 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -353,11 +353,6 @@
     "Experiment to have all APIs reflect the layout viewport. This will "
     "make window.scroll properties relative to the layout viewport.";
 
-const char kIphDemoModeChoiceName[] = "In-Product Help Demo Mode";
-
-const char kIphDemoModeChoiceDescription[] =
-    "Selects the In-Product Help demo mode.";
-
 const char kColorCorrectRenderingName[] = "Color correct rendering";
 
 const char kColorCorrectRenderingDescription[] =
@@ -1990,6 +1985,17 @@
 
 #endif  // defined(OS_ANDROID)
 
+//  In-Product Help flags
+
+#if defined(OS_ANDROID)
+
+const char kIphDemoModeChoiceName[] = "In-Product Help Demo Mode";
+
+const char kIphDemoModeChoiceDescription[] =
+    "Selects the In-Product Help demo mode.";
+
+#endif  // defined(OS_ANDROID)
+
 //  Settings window flags
 
 const char kSettingsWindowName[] = "Show settings in a window";