Remember previous keyboard type and use that when switching to "none" type.

BUG=484139

Review URL: https://codereview.chromium.org/1138103003

Cr-Commit-Position: refs/heads/master@{#330551}

content/public/android/java/src/org/chromium/content/browser/input/ImeAdapter.java

@@ -100,6 +100,7 @@ public class ImeAdapter {
 
     static char[] sSingleCharArray = new char[1];
     static KeyCharacterMap sKeyCharacterMap;
+    private static EditorInfo sPreviousOutAttrs;
 
     private long mNativeImeAdapterAndroid;
     private InputMethodManagerWrapper mInputMethodManagerWrapper;
@@ -133,7 +134,20 @@ public class ImeAdapter {
     public static class AdapterInputConnectionFactory {
         public AdapterInputConnection get(View view, ImeAdapter imeAdapter,
                 Editable editable, EditorInfo outAttrs) {
-            return new AdapterInputConnection(view, imeAdapter, editable, outAttrs);
+            AdapterInputConnection conn = new AdapterInputConnection(
+                    view, imeAdapter, editable, outAttrs);
+            // When switching between fields, the keyboard first reverts to a "none" type
+            // before changing to the type of the new field.  This can cause the keyboard
+            // layout to flicker back to the default layout on older Android versions (<5.0).
+            // To avoid this, we remember the previous settings and return those instead.
+            // http://crbug.com/484139
+            if (imeAdapter.getTextInputType() == TextInputType.NONE && sPreviousOutAttrs != null) {
+                outAttrs.inputType = sPreviousOutAttrs.inputType;
+                outAttrs.imeOptions = sPreviousOutAttrs.imeOptions;
+            } else {
+                sPreviousOutAttrs = outAttrs;
+            }
+            return conn;
         }
     }
 
@@ -287,6 +301,7 @@ public class ImeAdapter {
                     unzoomIfNeeded ? mViewEmbedder.getNewShowKeyboardReceiver() : null);
         }
         mViewEmbedder.onDismissInput();
+        sPreviousOutAttrs = null;
     }
 
     private boolean hasInputType() {