[WebLayer] Encapsulate SettingsAutofillAndPaymentsObserver in Ui

Context:
Since SettingsAutofillAndPaymentsObserver is autofill logic and
PaymentUiService is in charge of the autofill service, the observer
class should go into PaymentUiService.

Changes:
Moved SettingsAutofillAndPaymentsObserver from:
* CPRService#notifyPaymentUiOfPendingApps to PUiService#setPaymentApps
* CPRService#close to PUiService#close

Bug: 1025619
Change-Id: I224cf06276b26857775c26d2a030fd5fcc7d3295
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574602Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Commit-Queue: Liquan (Max) Gu <maxlg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834449}

chrome/android/java/src/org/chromium/chrome/browser/payments/ChromePaymentRequestService.java

@@ -557,7 +557,6 @@ public class ChromePaymentRequestService
         }
 
         mPaymentUiService.close();
-        SettingsAutofillAndPaymentsObserver.getInstance().unregisterObserver(mPaymentUiService);
 
         if (mPaymentHandlerHost != null) {
             mPaymentHandlerHost.destroy();
@@ -620,8 +619,6 @@ public class ChromePaymentRequestService
             RecordHistogram.recordSparseHistogram(
                     "PaymentRequest.MissingPaymentFields", missingFields);
         }
-
-        SettingsAutofillAndPaymentsObserver.getInstance().registerObserver(mPaymentUiService);
     }
 
     // Implements BrowserPaymentRequest:

chrome/android/java/src/org/chromium/chrome/browser/payments/SettingsAutofillAndPaymentsObserver.java

@@ -34,7 +34,7 @@ public class SettingsAutofillAndPaymentsObserver {
         void onAddressDeleted(String guid);
 
         /**
-         * Called when user updates or addes a credit card.
+         * Called when user updates or adds a credit card.
          *
          * @param card The updated or added card.
          */

chrome/android/java/src/org/chromium/chrome/browser/payments/ui/PaymentUiService.java

@@ -382,6 +382,8 @@ public class PaymentUiService implements SettingsAutofillAndPaymentsObserver.Obs
                 Section.PAYMENT_METHOD, apps.size(), !apps.isEmpty() && apps.get(0).isComplete());
 
         updateAppModifiedTotals();
+
+        SettingsAutofillAndPaymentsObserver.getInstance().registerObserver(this);
     }
 
     /** Set the AutofillPaymentAppCreator. */
@@ -1691,6 +1693,8 @@ public class PaymentUiService implements SettingsAutofillAndPaymentsObserver.Obs
             mPaymentMethodsSection = null;
         }
 
+        SettingsAutofillAndPaymentsObserver.getInstance().unregisterObserver(this);
+
         removeLeavingTabObservers();
         destroyCurrencyFormatters();
     }