PS - Showing permission prompt for activeTab

chrome/browser/chromeos/extensions/public_session_permission_helper.h

Index: chrome/browser/chromeos/extensions/public_session_permission_helper.h
diff --git a/chrome/browser/chromeos/extensions/public_session_permission_helper.h b/chrome/browser/chromeos/extensions/public_session_permission_helper.h
index 445f879aa0fd10a2c2dff7658f0ade8e4c69fc84..251337fa470535a6e93929a37b774e52b6bd7fe6 100644
--- a/chrome/browser/chromeos/extensions/public_session_permission_helper.h
+++ b/chrome/browser/chromeos/extensions/public_session_permission_helper.h
@@ -37,7 +37,8 @@ using PromptFactory = base::Callback<std::unique_ptr<ExtensionInstallPrompt>(
 //
 // This function sets up the prompt asking the user for additional
 // permission(s), handles the result, caches it, and then runs the callback with
-// the allowed permissions as the argument.
+// the allowed permissions as the argument. It returns true if this
+// permission(s) is already resolved, and false otherwise.
 //
 // The user will be prompted about a certain permission only once, and that
 // choice will be cached and used in any subsequent requests that use the same
@@ -47,14 +48,21 @@ using PromptFactory = base::Callback<std::unique_ptr<ExtensionInstallPrompt>(
 //
 // Caller must ensure that web_contents is valid. Must be called on UI thread.
 //
+// Callback can be null (permission_helper::RequestResolvedCallback()), in which
+// case it's not invoked but the permission prompt is still shown.
+//
 // Passing in a null prompt_factory (permission_helper::PromptFactory())
 // callback gets the default behaviour (ie. it is is used only for tests).
-void HandlePermissionRequest(const Extension& extension,
+bool HandlePermissionRequest(const Extension& extension,
                              const PermissionIDSet& requested_permissions,
                              content::WebContents* web_contents,
                              const RequestResolvedCallback& callback,
                              const PromptFactory& prompt_factory);
 
+// Returns true if user granted this permission to the extension.
+bool PermissionAllowed(const Extension* extension,

[Devlin, 2017/05/25 20:52:57]

I wonder if instead of this, we should have HandlePermissionRequest() return an
enum of { ALLOWED, BLOCKED, PENDING }.  Is it ever expected that a caller would
check PermissionAllowed() without HandlePermissionRequest?  If not, it could be
nice to bundle them and save the extra lookup.

[Ivan Šandrk, 2017/05/26 14:04:22]

Quite a good idea, but one problem - HandlePermissionRequest() can have two
requested permissions via a PermissionIDSet, so it's kinda troubling to return
the correct enum sequence. I could change the input parameter to a vector, but
that would require some refactoring around the codebase so I'd prefer not to do
it in this CL.

[Devlin, 2017/05/26 14:49:51]

Fair enough; this is fine. :)

+                       APIPermission::ID permission);
+
 // Used to completely reset state in between tests.
 void ResetPermissionsForTesting();