[Android] Add a workaround for setting empty IME compositions.

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

Index: content/public/android/java/src/org/chromium/content/browser/input/AdapterInputConnection.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/input/AdapterInputConnection.java b/content/public/android/java/src/org/chromium/content/browser/input/AdapterInputConnection.java
index 65958083eb8888ab89729cac576bbfd74be4458d..f2ae82906223fa1bbd9e267a65018cf07fdfa879 100644
--- a/content/public/android/java/src/org/chromium/content/browser/input/AdapterInputConnection.java
+++ b/content/public/android/java/src/org/chromium/content/browser/input/AdapterInputConnection.java
@@ -8,6 +8,7 @@ import android.os.SystemClock;
 import android.text.Editable;
 import android.text.InputType;
 import android.text.Selection;
+import android.text.TextUtils;
 import android.util.Log;
 import android.view.KeyEvent;
 import android.view.View;
@@ -212,6 +213,7 @@ public class AdapterInputConnection extends BaseInputConnection {
     @Override
     public boolean setComposingText(CharSequence text, int newCursorPosition) {
         if (DEBUG) Log.w(TAG, "setComposingText [" + text + "] [" + newCursorPosition + "]");
+        if (maybePerformEmptyCompositionWorkaround(text)) return true;
         super.setComposingText(text, newCursorPosition);
         updateSelectionIfRequired();
         return mImeAdapter.checkCompositionQueueAndCallNative(text.toString(),
@@ -224,6 +226,7 @@ public class AdapterInputConnection extends BaseInputConnection {
     @Override
     public boolean commitText(CharSequence text, int newCursorPosition) {
         if (DEBUG) Log.w(TAG, "commitText [" + text + "] [" + newCursorPosition + "]");
+        if (maybePerformEmptyCompositionWorkaround(text)) return true;
         super.commitText(text, newCursorPosition);
         updateSelectionIfRequired();
         return mImeAdapter.checkCompositionQueueAndCallNative(text.toString(),
@@ -446,6 +449,33 @@ public class AdapterInputConnection extends BaseInputConnection {
         return mImeAdapter.getInputMethodManagerWrapper();
     }
 
+    /**
+     * This method works around the issue crbug.com/373934 where Blink does not cancel
+     * the composition when we send a commit with the empty text.
+     *
+     * TODO(aurimas) Remove this once crbug.com/373934 is fixed.
+     *
+     * @param text Text that software keyboard requested to commit.
+     * @return Whether the workaround was performed.
+     */
+    private boolean maybePerformEmptyCompositionWorkaround(CharSequence text) {
+        int selectionStart = Selection.getSelectionStart(mEditable);
+        int selectionEnd = Selection.getSelectionEnd(mEditable);
+        int compositionStart = getComposingSpanStart(mEditable);
+        int compositionEnd = getComposingSpanEnd(mEditable);
+        if (TextUtils.isEmpty(text) && (selectionStart == selectionEnd)
+                && compositionStart != INVALID_COMPOSITION
+                && compositionEnd != INVALID_COMPOSITION) {
+            beginBatchEdit();
+            finishComposingText();
+            int selection = Selection.getSelectionStart(mEditable);
+            deleteSurroundingText(selection - compositionStart, selection - compositionEnd);
+            endBatchEdit();
+            return true;
+        }
+        return false;
+    }
+
     @VisibleForTesting
     static class ImeState {
         public final String text;