Signin: Reuse existing "update gms" dialogs when possible.

chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java

Index: chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java
index 55e5a68376ce06d753fa4f97f6690e7474bb5498..87ea21e1d1ecac220c9b2d0a41aa5ff1b544d35e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/externalauth/UserRecoverableErrorHandler.java
@@ -138,6 +138,11 @@ public abstract class UserRecoverableErrorHandler {
         private final boolean mCancelable;
 
         /**
+         * Error code from Google Play Services.

[Bernhard Bauer, 2017/01/12 10:14:33]

Nit: "Last error code [...]"?

[estevenson, 2017/01/12 19:52:33]

Done.

+         */
+        private int mErrorCode;
+
+        /**
          * Create a new Modal Dialog handler for the specified activity and error code. The
          * specified activity may be used to launch the dialog via
          * {@link Activity#startActivityForResult(android.content.Intent, int)} and also to receive
@@ -159,8 +164,16 @@ public abstract class UserRecoverableErrorHandler {
          */
         @Override
         protected final void handle(final Context context, final int errorCode) {
-            mDialog = GoogleApiAvailability.getInstance().getErrorDialog(
-                    mActivity, errorCode, NO_RESPONSE_REQUIRED);
+            // Assume old dialogs generated by the same error handler are obsolete when an error
+            // with a different error code is encountered.
+            if (mErrorCode != errorCode) {
+                cancelDialog();
+            }
+            if (mDialog == null) {
+                mDialog = GoogleApiAvailability.getInstance().getErrorDialog(
+                        mActivity, errorCode, NO_RESPONSE_REQUIRED);
+                mErrorCode = errorCode;
+            }
             // This can happen if |errorCode| is ConnectionResult.SERVICE_INVALID.
             if (mDialog != null) {
                 mDialog.setCancelable(mCancelable);
@@ -175,6 +188,7 @@ public abstract class UserRecoverableErrorHandler {
         public void cancelDialog() {
             if (mDialog != null) {
                 mDialog.cancel();
+                mDialog = null;
             }
         }
     }