[iOS] Fixing a crash in PasswordManager::UpdateStateOnUserInput.

Driver check needs to be omitted on iOS, as cross-origin frames support
is not implemented yet for PasswordManager and driver pointer is
intentionally set to null sometimes.

Bug: 1065196
Change-Id: I898b16a27ff478fd556c06322f00f2482fa1749e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2129535Reviewed-by: Vadym Doroshenko  <dvadym@chromium.org>
Commit-Queue: Maria Kazinova <kazinova@google.com>
Cr-Commit-Position: refs/heads/master@{#755296}

components/password_manager/core/browser/password_form_manager.cc

@@ -506,6 +506,11 @@ bool PasswordFormManager::UpdateStateOnUserInput(
     PresaveGeneratedPasswordInternal(observed_form_, generated_password);
   return true;
 }
+
+void PasswordFormManager::SetDriver(
+    const base::WeakPtr<PasswordManagerDriver>& driver) {
+  driver_ = driver;
+}
 #endif  // defined(OS_IOS)
 
 std::unique_ptr<PasswordFormManager> PasswordFormManager::Clone() {

components/password_manager/core/browser/password_form_manager.h

@@ -189,6 +189,8 @@ class PasswordFormManager : public PasswordFormManagerForUI,
   bool UpdateStateOnUserInput(const base::string16& form_identifier,
                               const base::string16& field_identifier,
                               const base::string16& field_value);
+
+  void SetDriver(const base::WeakPtr<PasswordManagerDriver>& driver);
 #endif  // defined(OS_IOS)
 
   // Create a copy of |*this| which can be passed to the code handling

components/password_manager/core/browser/password_manager.cc

@@ -1070,9 +1070,15 @@ void PasswordManager::RecordProvisionalSaveFailure(
 // TODO(https://crbug.com/831123): Implement creating missing
 // PasswordFormManager when PasswordFormManager is gone.
 PasswordFormManager* PasswordManager::GetMatchedManager(
-    const PasswordManagerDriver* driver,
+    PasswordManagerDriver* driver,
     const FormData& form) {
   for (auto& form_manager : form_managers_) {
+// Until support of cross-origin iframes is implemented, there is only one
+// driver on iOS. It needs to be set in order for filling to work.
+#if defined(OS_IOS)
+    if (driver && !form_manager->GetDriver())
+      form_manager->SetDriver(driver->AsWeakPtr());
+#endif
     if (form_manager->DoesManage(form, driver))
       return form_manager.get();
   }

components/password_manager/core/browser/password_manager.h

@@ -303,7 +303,7 @@ class PasswordManager : public FormSubmissionObserver {
 
   // Returns the manager which manages |form|. |driver| is needed to determine
   // the match. Returns nullptr when no matched manager is found.
-  PasswordFormManager* GetMatchedManager(const PasswordManagerDriver* driver,
+  PasswordFormManager* GetMatchedManager(PasswordManagerDriver* driver,
                                          const autofill::FormData& form);
 
   // Log a frame (main frame, iframe) of a submitted password form.