Chromium: Clipboard android code uses unsafe jni and is buggy

This change removes most of the explicit JNI manipulation from the
clipboard_android.cc implementation and replaces it with modernized
generated JNI stubs derived from a Java implementation class.
This change also migrates away from the deprecated
android.text.ClipboardManager to android.content.ClipboardManager,
which is the modern equivalent.

Note that the old implementation of clipboard_android.cc relied
almost exclusively upon deprecated functionality in the clipboard,
namely (1) assuming there is only one clip, (2) always treating
that clip as plain text and (3, indavertently) coercing non-text
content to text (such as URI objects in the clipboard). In this
change, we have NOT changed these behaviors - we have merely
moved away from the deprecated APIs. It will be left to another
change to perform a more invasive rewiring of the clipboard
implementation here that more closely aligns with the modern
capabilities of the Android clipboard (e.g., supporting bitmaps,
HTML text, and so on).

BUG=180476
TBR=ben

Review URL: https://chromiumcodereview.appspot.com/12633009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@188458 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 113 insertions, 0 deletions

diff --git a/ui/android/java/src/org/chromium/ui/Clipboard.java b/ui/android/java/src/org/chromium/ui/Clipboard.java
new file mode 100644
index 0000000..a66fa3d
--- /dev/null
+++ b/ui/android/java/src/org/chromium/ui/Clipboard.java
@@ -0,0 +1,111 @@
+// Copyright (c) 2013 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;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+import android.content.ClipData;
+import android.content.ClipboardManager;
+import android.content.Context;
+import android.text.TextUtils;
+
+/**
+ * Simple proxy that provides C++ code with an access pathway to the Android
+ * clipboard.
+ */
+@JNINamespace("ui")
+public class Clipboard {
+    // Necessary for coercing clipboard contents to text if they require
+    // access to network resources, etceteras (e.g., URI in clipboard)
+    private final Context mContext;
+
+    private final ClipboardManager mClipboardManager;
+
+    /**
+     * Use the factory constructor instead.
+     *
+     * @param context for accessing the clipboard
+     */
+    private Clipboard(final Context context) {
+        mContext = context;
+        mClipboardManager = (ClipboardManager)
+                context.getSystemService(Context.CLIPBOARD_SERVICE);
+    }
+
+    /**
+     * Returns a new Clipboard object bound to the specified context.
+     *
+     * @param context for accessing the clipboard
+     * @return the new object
+     */
+    @CalledByNative
+    private static Clipboard create(final Context context) {
+        return new Clipboard(context);
+    }
+
+    /**
+     * Emulates the behavior of the now-deprecated
+     * {@link android.text.ClipboardManager#getText()} by invoking
+     * {@link android.content.ClipData.Item#coerceToText(Context)} on the first
+     * item in the clipboard (if any) and returning the result as a string.
+     * <p>
+     * This is quite different than simply calling {@link Object#toString()} on
+     * the clip; consumers of this API should familiarize themselves with the
+     * process described in
+     * {@link android.content.ClipData.Item#coerceToText(Context)} before using
+     * this method.
+     *
+     * @return a string representation of the first item on the clipboard, if
+     *         the clipboard currently has an item and coercion of the item into
+     *         a string is possible; otherwise, <code>null</code>
+     */
+    @SuppressWarnings("javadoc")
+    @CalledByNative
+    private String getCoercedText() {
+        final ClipData clip = mClipboardManager.getPrimaryClip();
+        if (clip != null && clip.getItemCount() > 0) {
+            final CharSequence sequence = clip.getItemAt(0).coerceToText(mContext);
+            if (sequence != null) {
+                return sequence.toString();
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Emulates the behavior of the now-deprecated
+     * {@link android.text.ClipboardManager#setText(CharSequence)}, setting the
+     * clipboard's current primary clip to a plain-text clip that consists of
+     * the specified string.
+     *
+     * @param text will become the content of the clipboard's primary clip
+     */
+    @SuppressWarnings("javadoc")
+    @CalledByNative
+    private void setText(final String text) {
+        mClipboardManager.setPrimaryClip(ClipData.newPlainText(null, text));
+    }
+
+    /**
+     * Approximates the behavior of the now-deprecated
+     * {@link android.text.ClipboardManager#hasText()}, returning true if and
+     * only if the clipboard has a primary clip and that clip contains a plain
+     * non-empty text entry (without attempting coercion - URLs and intents
+     * will cause this method to return false).
+     *
+     * @return as described above
+     */
+    @SuppressWarnings("javadoc")
+    @CalledByNative
+    private boolean hasPlainText() {
+        final ClipData clip = mClipboardManager.getPrimaryClip();
+        if (clip != null && clip.getItemCount() > 0) {
+            final CharSequence text = clip.getItemAt(0).getText();
+            return !TextUtils.isEmpty(text);
+        }
+        return false;
+    }
+}
diff --git a/ui/android/ui_jni_registrar.cc b/ui/android/ui_jni_registrar.cc
index 37a3fb8..048d874 100644
--- a/ui/android/ui_jni_registrar.cc
+++ b/ui/android/ui_jni_registrar.cc
@@ -6,6 +6,7 @@
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_registrar.h"
+#include "ui/base/clipboard/clipboard_android_initialization.h"
 #include "ui/gfx/android/device_display_info.h"
 #include "ui/gfx/android/java_bitmap.h"
 #include "ui/gfx/android/window_android.h"
@@ -17,6 +18,7 @@ static base::android::RegistrationMethod kUiRegisteredMethods[] = {
   { "DeviceDisplayInfo", gfx::DeviceDisplayInfo::RegisterDeviceDisplayInfo },
   { "JavaBitmap", gfx::JavaBitmap::RegisterJavaBitmap },
   { "NativeWindow", ui::WindowAndroid::RegisterWindowAndroid },
+  { "Clipboard", ui::RegisterClipboardAndroid },
 };
 
 bool RegisterJni(JNIEnv* env) {