Support InputMethodManager#updateCursorAnchorInfo for Android 5.0

ui/android/java/src/org/chromium/ui/base/CursorAnchorInfoBuilder.java

Index: ui/android/java/src/org/chromium/ui/base/CursorAnchorInfoBuilder.java
diff --git a/ui/android/java/src/org/chromium/ui/base/CursorAnchorInfoBuilder.java b/ui/android/java/src/org/chromium/ui/base/CursorAnchorInfoBuilder.java
new file mode 100644
index 0000000000000000000000000000000000000000..ffa89179b37bc01beef50a2c325779dc71653621
--- /dev/null
+++ b/ui/android/java/src/org/chromium/ui/base/CursorAnchorInfoBuilder.java
@@ -0,0 +1,78 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.ui.base;
+
+import android.graphics.Matrix;
+import android.os.Build;
+import android.view.inputmethod.CursorAnchorInfo;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+import java.lang.CharSequence;
+
+/**
+ * A simple class to allow native code to call instance methods of {@link CursorAnchorInfo.Builder}.
+ * This class itself is designed to be stateless. All the methods are thread-safe.
+ */
+@JNINamespace("ui")
+public final class CursorAnchorInfoBuilder {
+
+    private static final Matrix sMatrix = new Matrix();
+
+    @CalledByNative
+    public static CursorAnchorInfo.Builder create() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
+            return null;
+        }
+        return new CursorAnchorInfo.Builder();
+    }
+
+    @CalledByNative
+    public static void reset(CursorAnchorInfo.Builder builder) {
+        builder.reset();
+    }
+
+    @CalledByNative
+    public static void setSelectionRange(CursorAnchorInfo.Builder builder, int newStart,
+            int newEnd) {
+        builder.setSelectionRange(newStart, newEnd);
+    }
+
+    @CalledByNative
+    public static void setComposingText(CursorAnchorInfo.Builder builder, int composingTextStart,
+            CharSequence composingText) {
+        builder.setComposingText(composingTextStart, composingText);
+    }
+
+    @CalledByNative
+    public static void setInsertionMarkerLocation(CursorAnchorInfo.Builder builder,
+            float horizontalPosition, float lineTop, float lineBaseline, float lineBottom,
+            int flags) {
+        builder.setInsertionMarkerLocation(horizontalPosition, lineTop, lineBaseline, lineBottom,
+                flags);
+    }
+
+    @CalledByNative
+    public static void addCharacterBounds(CursorAnchorInfo.Builder builder, int index, float left,
+            float top, float right, float bottom, int flags) {
+        builder.addCharacterBounds(index, left, top, right, bottom, flags);
+    }
+
+    @CalledByNative
+    public static void setScaleAndTranslate(CursorAnchorInfo.Builder builder, float scale,
+            float translateX, float translateY) {
+        synchronized (sMatrix) {

[jdduke (slow), 2015/01/20 21:17:34]

This should always be called from the UI thread, so we can probably avoid the
synchronization and just do |ThreadUtils.assertOnUIThread|.

+            sMatrix.setScale(scale, scale);
+            sMatrix.postTranslate(translateX, translateY);
+            builder.setMatrix(sMatrix);
+        }
+    }
+
+    @CalledByNative
+    public static CursorAnchorInfo build(CursorAnchorInfo.Builder builder) {
+        return builder.build();
+    }
+}