Fix setComposingText when newCursorPosition != 1

third_party/WebKit/Source/core/editing/PlainTextRange.cpp

Index: third_party/WebKit/Source/core/editing/PlainTextRange.cpp
diff --git a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
index 7cfb84d3ba034f28437dd9c0c45e3f34382c3cb6..46a923c76949e4a1c31cc9adb84eb6fd4e0bea50 100644
--- a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
+++ b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
@@ -148,8 +148,16 @@ EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRan
         docTextPosition += len;
     }
 
-    if (!startRangeFound)
-        return EphemeralRange();
+    if (!startRangeFound) {
+        // startRangeFound = start() >= docTextPosition && start() <= docTextPosition + len.
+        // The former condition is related to the left boundary, and the latter to the right boundary.
+        // Since we assert that end()>=start()>=0, and docTextPosition==0 before the loop starts,
+        // so startRangeFound is false if and only if new cursor position exceeds the right boundary.
+        // In that case, the cursor should stay at the right boundary, because EditText, the component
+        // in Android, behaves in that way.

[Changwan Ryu, 2016/04/05 07:50:37]

how about renaming startRangeFound as startOutOfBound and not adding any comment
here.

[yabinh, 2016/04/05 08:06:41]

Acknowledged.

+        resultStart = textRunEndPosition;
+        resultEnd = textRunEndPosition;
+    }
 
     if (length() && end() > docTextPosition) { // end() is out of bounds
         resultEnd = textRunEndPosition;