Return null when selected text is empty

InputConnection#getSelectedText() should return null when the selection
is empty. ThreadedInputConnection was not doing this correctly, and confused
some OEM keyboards.

BUG=638201

Review-Url: https://codereview.chromium.org/2279293002
Cr-Commit-Position: refs/heads/master@{#414821}

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

@@ -53,6 +53,7 @@ public class TextInputState {
     }
 
     public CharSequence getSelectedText() {
+        if (mSelection.start() == mSelection.end()) return null;
         return TextUtils.substring(mText, mSelection.start(), mSelection.end());
     }
 

content/public/android/javatests/src/org/chromium/content/browser/input/ImeTest.java

@@ -136,7 +136,7 @@ public class ImeTest extends ContentShellTestBase {
         setSelection(2, 2);
         waitAndVerifyUpdateSelection(2, 2, 2, -1, -1);
         deleteSurroundingText(0, 0);
-        assertTextsAroundCursor("he", "", "llo");
+        assertTextsAroundCursor("he", null, "llo");
     }
 
     // When newCursorPosition != 1, setComposingText doesn't work for ReplicaInputConnection
@@ -200,12 +200,12 @@ public class ImeTest extends ContentShellTestBase {
         // With previous composition.
         setComposingText("", -3);
         waitAndVerifyUpdateSelection(2, 2, 2, -1, -1);
-        assertTextsAroundCursor("he", "", "llo");
+        assertTextsAroundCursor("he", null, "llo");
 
         // Without previous composition.
         setComposingText("", 3);
         waitAndVerifyUpdateSelection(3, 4, 4, -1, -1);
-        assertTextsAroundCursor("hell", "", "o");
+        assertTextsAroundCursor("hell", null, "o");
     }
 
     @SmallTest
@@ -229,7 +229,7 @@ public class ImeTest extends ContentShellTestBase {
         commitText("", 1);
         waitAndVerifyUpdateSelection(5, 3, 3, -1, -1);
 
-        assertTextsAroundCursor("hel", "", "");
+        assertTextsAroundCursor("hel", null, "");
     }
 
     @SmallTest
@@ -245,11 +245,11 @@ public class ImeTest extends ContentShellTestBase {
         waitAndVerifyUpdateSelection(1, 1, 1, -1, -1);
         // The second new line is not a user visible/editable one, it is a side-effect of Blink
         // using <br> internally. This only happens when \n is at the end.
-        assertTextsAroundCursor("\n", "", "\n");
+        assertTextsAroundCursor("\n", null, "\n");
 
         commitText("world", 1);
         waitAndVerifyUpdateSelection(2, 6, 6, -1, -1);
-        assertTextsAroundCursor("\nworld", "", "");
+        assertTextsAroundCursor("\nworld", null, "");
     }
 
     @SmallTest
@@ -329,10 +329,6 @@ public class ImeTest extends ContentShellTestBase {
         assertEquals(before, getTextBeforeCursor(100, 0));
 
         CharSequence actualSelected = getSelectedText(0);
-        if (usingReplicaInputConnection() && TextUtils.isEmpty(actualSelected)) {
-            // ReplicaInputConnection will return null but ChromiumInputConnection will return "".
-            actualSelected = "";
-        }
         assertEquals(selected, actualSelected);
 
         if (usingReplicaInputConnection() && after.equals("\n")) {
@@ -603,7 +599,7 @@ public class ImeTest extends ContentShellTestBase {
 
         cut();
         waitAndVerifyUpdateSelection(2, 1, 1, -1, -1);
-        assertTextsAroundCursor("s", "", "ul");
+        assertTextsAroundCursor("s", null, "ul");
         assertClipboardContents(getActivity(), "narf");
     }
 
@@ -623,7 +619,7 @@ public class ImeTest extends ContentShellTestBase {
         paste();
         // Paste is a two step process when there is a non-zero selection.
         waitAndVerifyUpdateSelection(0, 5, 5, -1, -1);
-        assertTextsAroundCursor("blarg", "", "");
+        assertTextsAroundCursor("blarg", null, "");
 
         setSelection(3, 5);
         waitAndVerifyUpdateSelection(1, 3, 5, -1, -1);
@@ -633,11 +629,11 @@ public class ImeTest extends ContentShellTestBase {
         // Paste is a two step process when there is a non-zero selection.
         waitAndVerifyUpdateSelection(2, 3, 3, -1, -1);
         waitAndVerifyUpdateSelection(3, 8, 8, -1, -1);
-        assertTextsAroundCursor("blablarg", "", "");
+        assertTextsAroundCursor("blablarg", null, "");
 
         paste();
         waitAndVerifyUpdateSelection(4, 13, 13, -1, -1);
-        assertTextsAroundCursor("blablargblarg", "", "");
+        assertTextsAroundCursor("blablargblarg", null, "");
     }
 
     // Chrome can crash after pasting long text into textarea, becasue there is an overflow bug in
@@ -713,7 +709,7 @@ public class ImeTest extends ContentShellTestBase {
 
         setSelection(1, 1);
         waitAndVerifyUpdateSelection(2, 1, 1, -1, -1);
-        assertTextsAroundCursor("h", "", "llo ");
+        assertTextsAroundCursor("h", null, "llo ");
 
         setComposingRegion(0, 4);
         waitAndVerifyUpdateSelection(3, 1, 1, 0, 4);
@@ -723,7 +719,7 @@ public class ImeTest extends ContentShellTestBase {
 
         commitText("\n", 1);
         waitAndVerifyUpdateSelection(5, 2, 2, -1, -1);
-        assertTextsAroundCursor("h\n", "", "llo ");
+        assertTextsAroundCursor("h\n", null, "llo ");
     }
 
     // http://crbug.com/445499
@@ -807,7 +803,7 @@ public class ImeTest extends ContentShellTestBase {
 
         commitText(smiley, 1);
         waitAndVerifyUpdateSelection(0, 2, 2, -1, -1);
-        assertTextsAroundCursor(smiley, "", "");
+        assertTextsAroundCursor(smiley, null, "");
 
         // DEL, sent via dispatchKeyEvent like it is in Android WebView or a physical keyboard.
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL));
@@ -880,13 +876,13 @@ public class ImeTest extends ContentShellTestBase {
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_ENTER));
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_ENTER));
         waitAndVerifyUpdateSelection(1, 2, 2, -1, -1);
-        assertTextsAroundCursor("a\n", "", "\n");
+        assertTextsAroundCursor("a\n", null, "\n");
 
         // Type 'b'.
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_B));
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_B));
         waitAndVerifyUpdateSelection(2, 3, 3, -1, -1);
-        assertTextsAroundCursor("a\nb", "", "");
+        assertTextsAroundCursor("a\nb", null, "");
     }
 
     @SmallTest
@@ -989,11 +985,11 @@ public class ImeTest extends ContentShellTestBase {
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_ENTER));
         dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_ENTER));
         waitAndVerifyUpdateSelection(1, 6, 6, -1, -1);
-        assertTextsAroundCursor("hello\n", "", "\n");
+        assertTextsAroundCursor("hello\n", null, "\n");
 
         commitText("world", 1);
         waitAndVerifyUpdateSelection(2, 11, 11, -1, -1);
-        assertTextsAroundCursor("hello\nworld", "", "");
+        assertTextsAroundCursor("hello\nworld", null, "");
     }
 
     @SmallTest
@@ -1017,7 +1013,7 @@ public class ImeTest extends ContentShellTestBase {
 
         commitText("world", 1);
         waitAndVerifyUpdateSelection(3, 11, 11, -1, -1);
-        assertTextsAroundCursor("hello\nworld", "", "");
+        assertTextsAroundCursor("hello\nworld", null, "");
     }
 
     @SmallTest
@@ -1048,7 +1044,7 @@ public class ImeTest extends ContentShellTestBase {
             // make take some round trip time until we get the correct value.
             waitUntilGetCharacterBeforeCursorBecomes("l");
         } else {
-            assertTextsAroundCursor("hell", "", "o");
+            assertTextsAroundCursor("hell", null, "o");
         }
     }
 
@@ -1100,7 +1096,7 @@ public class ImeTest extends ContentShellTestBase {
 
         cut();
         waitAndVerifyUpdateSelection(2, 0, 0, -1, -1);
-        assertTextsAroundCursor("", "", "");
+        assertTextsAroundCursor("", null, "");
 
         DOMUtils.longPressNode(this, mContentViewCore, "input_text");
         CriteriaHelper.pollUiThread(new Criteria() {

content/public/android/junit/src/org/chromium/content/browser/input/TextInputStateTest.java

@@ -27,7 +27,7 @@ public class TextInputStateTest {
         assertEquals("hel", state.getTextBeforeSelection(3));
         assertEquals("el", state.getTextBeforeSelection(2));
         assertEquals("", state.getTextBeforeSelection(0));
-        assertEquals("", state.getSelectedText());
+        assertEquals(null, state.getSelectedText());
     }
 
     @Test