Fix Android strict-mode violation in GeoLocation info bar.

chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc

Index: chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc
diff --git a/chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc b/chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc
index afb213cf34353c11985c078dda19866207ee32e1..33b3df66afab2e629ac2048214d7234f2cf32a5c 100644
--- a/chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc
+++ b/chrome/browser/geolocation/chrome_geolocation_permission_context_android.cc
@@ -6,6 +6,7 @@
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/android/google_location_settings_helper.h"
+#include "chrome/browser/content_settings/permission_request_id.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
@@ -21,23 +22,61 @@ ChromeGeolocationPermissionContextAndroid::
     ~ChromeGeolocationPermissionContextAndroid() {
 }
 
-void ChromeGeolocationPermissionContextAndroid::DecidePermission(
+void ChromeGeolocationPermissionContextAndroid::CallSuperDecidePermission(

[bulach, 2013/09/12 09:18:29]

thanks for the explanation!
how about "ProceedDecidePermissionFlow"? more below..

[acleung1, 2013/09/17 00:08:45]

Done.

     const PermissionRequestID& id,
     const GURL& requesting_frame,
     const GURL& embedder,
     base::Callback<void(bool)> callback) {
+  // Super class implementation expects everything in UI thread instead.
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  ChromeGeolocationPermissionContext::DecidePermission(
+      id, requesting_frame, embedder, callback);
+}
 
+void ChromeGeolocationPermissionContextAndroid::CheckMasterLocation(
+    const PermissionRequestID& id,
+    const GURL& requesting_frame,
+    const GURL& embedder,
+    base::Callback<void(bool)> callback) {
   // Check to see if the feature in its entirety has been disabled.
   // This must happen before other services (e.g. tabs, extensions)
   // get an opportunity to allow the geolocation request.
-  if (!google_location_settings_helper_->IsMasterLocationSettingEnabled()) {
-    PermissionDecided(id, requesting_frame, embedder, callback, false);
-    return;
+  bool enabled =
+      google_location_settings_helper_->IsMasterLocationSettingEnabled();
+
+  // Regardless of what the master setting is, we still need to
+  // go back to the UI thread for the rest of the bookkeeping.

[bulach, 2013/09/12 09:18:29]

Perhaps a more detailed explanation would help clarify:

// The flow for geolocation permission on android is:
// - ChromeGeolocationPermissionContextAndroid::DecidePermission
// intercepts the flow in the UI thread, and posts task
// to the blocking pool to CheckMasterLocation (in order to
// avoid strict-mode violation).
// - At this point the master location permission is either:
// -- enabled, in which we case it proceeds the normal flow
// via ChromeGeolocationPermissionContext (which may create infobars, etc.).
// -- disabled, in which case the permission is already decided.
//
// In either case, ChromeGeolocationPermissionContext expects these
// in the UI thread.

[acleung1, 2013/09/17 00:08:45]

Done.

+  base::Closure ui_closure;
+  if (enabled) {
+    ui_closure = base::Bind(
+        &ChromeGeolocationPermissionContextAndroid::CallSuperDecidePermission,

[bulach, 2013/09/12 09:18:29]

so if you agree with the comment above, I think "ProceedDecidePermissionFlow"
would be clearer..

[acleung1, 2013/09/17 00:08:45]

Done.

+        base::Unretained(this), id, requesting_frame, embedder, callback);
+  } else {
+    ui_closure = base::Bind(
+        &ChromeGeolocationPermissionContextAndroid::PermissionDecided,
+        base::Unretained(this), id,
+        requesting_frame, embedder, callback, false);
   }
 
-  ChromeGeolocationPermissionContext::DecidePermission(id, requesting_frame,
-                                                       embedder, callback);
+  // This method is executed from the BlockingPool, post the result
+  // back to the UI thread.
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,ui_closure);

[bulach, 2013/09/12 09:18:29]

nit: space after comma, s/,ui_clo/, ui_clo/

[acleung1, 2013/09/17 00:08:45]

Done.

+}
+
+void ChromeGeolocationPermissionContextAndroid::DecidePermission(
+    const PermissionRequestID& id,
+    const GURL& requesting_frame,
+    const GURL& embedder,
+    base::Callback<void(bool)> callback) {
+
+  // Called on the UI thread. However, do the work on a separate thread
+  // to avoid strict mode violation.
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  content::BrowserThread::PostBlockingPoolTask(FROM_HERE,
+      base::Bind(
+          &ChromeGeolocationPermissionContextAndroid::CheckMasterLocation,
+  base::Unretained(this), id, requesting_frame, embedder, callback));

[bulach, 2013/09/12 09:18:29]

nit: indent

[acleung1, 2013/09/17 00:08:45]

Done.

 }
 
 void ChromeGeolocationPermissionContextAndroid::PermissionDecided(
@@ -46,7 +85,6 @@ void ChromeGeolocationPermissionContextAndroid::PermissionDecided(
     const GURL& embedder,
     base::Callback<void(bool)> callback,
     bool allowed) {
-  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   // If Google Apps Location setting is turned off then we ignore
   // the 'allow' website setting for this site and instead show
   // the infobar to go back to the 'settings' to turn it back on.