Change a heuristic and add a log.

The heuristic in RichInputConnection makes little sense
when textLength > mExpectedSelStart but we have
more than 1024 characters of text. If there are that many,
it's about 100% sure that 1024 is not the correct cursor
position. With no good guess, we'll just continue trusting
the app, even though we know it's lying : at least it will
make the problem visible to the app author.

Also, there have been a lot of confusion about initialSelStart
and initialSelEnd. The keyboard should log them so that
it helps us and editor authors debug more easily these
common problems.

Issue #65170 in AOSP and
Bug: 12772035
Change-Id: I6665a16c9f2832d33ee323f033bb38bcc092a3b4

java/src/com/android/inputmethod/latin/LatinIME.java

@@ -751,6 +751,8 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
                     + ", word caps = "
                     + ((editorInfo.inputType & InputType.TYPE_TEXT_FLAG_CAP_WORDS) != 0));
         }
+        Log.i(TAG, "Starting input. Cursor position = "
+                + editorInfo.initialSelStart + "," + editorInfo.initialSelEnd);
         if (ProductionFlag.USES_DEVELOPMENT_ONLY_DIAGNOSTICS) {
             final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
             ResearchLogger.latinIME_onStartInputViewInternal(editorInfo, prefs);

java/src/com/android/inputmethod/latin/RichInputConnection.java

@@ -847,9 +847,9 @@ public final class RichInputConnection {
             mExpectedSelStart = mExpectedSelEnd = Constants.NOT_A_CURSOR_POSITION;
         } else {
             final int textLength = textBeforeCursor.length();
-            if (textLength > mExpectedSelStart
-                    || (textLength < Constants.EDITOR_CONTENTS_CACHE_SIZE
-                            && mExpectedSelStart < Constants.EDITOR_CONTENTS_CACHE_SIZE)) {
+            if (textLength < Constants.EDITOR_CONTENTS_CACHE_SIZE
+                    && (textLength > mExpectedSelStart
+                            ||  mExpectedSelStart < Constants.EDITOR_CONTENTS_CACHE_SIZE)) {
                 // It should not be possible to have only one of those variables be
                 // NOT_A_CURSOR_POSITION, so if they are equal, either the selection is zero-sized
                 // (simple cursor, no selection) or there is no cursor/we don't know its pos