Support dragging texts into Android WebView.

ui/base/dragdrop/os_exchange_data_provider_android.cc

+// Copyright 2016 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.
+
+#include "ui/base/dragdrop/os_exchange_data_provider_android.h"
+
+namespace ui {
+
+OSExchangeDataProviderAndroid::OSExchangeDataProviderAndroid() {}
+
+OSExchangeDataProviderAndroid::~OSExchangeDataProviderAndroid() {}
+
+OSExchangeData::Provider* OSExchangeDataProviderAndroid::Clone() const {
+  OSExchangeDataProviderAndroid* provider = new OSExchangeDataProviderAndroid();
+  provider->string_ = string_;
+
+  return provider;
+}
+
+void OSExchangeDataProviderAndroid::MarkOriginatedFromRenderer() {
+  // no-op.

[Ted C, 2016/02/25 18:38:53]

should all of these be marked as NOTIMPLEMENTED() instead of no op?

[hush (inactive), 2016/02/27 01:46:14]

yes. That would be good to catch any unexpected calls to these methods. (there
shouldn't be any though)

+}
+
+bool OSExchangeDataProviderAndroid::DidOriginateFromRenderer() const {
+  return false;
+}
+
+void OSExchangeDataProviderAndroid::SetString(const base::string16& string) {
+  string_ = string;
+}
+
+void OSExchangeDataProviderAndroid::SetURL(const GURL& url,
+                                           const base::string16& title) {
+  // no op
+}
+
+void OSExchangeDataProviderAndroid::SetFilename(const base::FilePath& path) {
+  // no op
+}
+
+void OSExchangeDataProviderAndroid::SetFilenames(
+    const std::vector<ui::FileInfo>& filenames) {
+  // no op
+}
+
+void OSExchangeDataProviderAndroid::SetPickledData(
+    const ui::Clipboard::FormatType& format,
+    const base::Pickle& pickle) {
+  // no op.
+}
+
+bool OSExchangeDataProviderAndroid::GetString(base::string16* string) const {
+  *string = string_;
+  return string_.size() > 0;

[aelias_OOO_until_Jul13, 2016/02/25 20:58:00]

!string_.empty() (likewise in HasString())

[hush (inactive), 2016/02/27 01:46:14]

I changed the logic a little. I used a format_ integer flag to track whether any
strings has been set. That's because there is a meaningful difference between a
DataProvider with an empty string VS a DataProvider without any string.

On Android, when the drag starts, we know the MIME type of dragged object (which
is string), but we don't know what the string is. So we will need to set an
empty string on the DataProvider to indicate that the DataProvider contains a
string type.

+}
+
+bool OSExchangeDataProviderAndroid::GetURLAndTitle(
+    ui::OSExchangeData::FilenameToURLPolicy policy,
+    GURL* url,
+    base::string16* title) const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::GetFilename(base::FilePath* path) const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::GetFilenames(
+    std::vector<ui::FileInfo>* filenames) const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::GetPickledData(
+    const ui::Clipboard::FormatType& format,
+    base::Pickle* pickle) const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::HasString() const {
+  return string_.size() > 0;
+}
+
+bool OSExchangeDataProviderAndroid::HasURL(
+    ui::OSExchangeData::FilenameToURLPolicy policy) const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::HasFile() const {
+  return false;
+}
+
+bool OSExchangeDataProviderAndroid::HasCustomFormat(
+    const ui::Clipboard::FormatType& format) const {
+  return false;
+}
+
+// static
+OSExchangeData::Provider* OSExchangeData::CreateProvider() {
+  return new OSExchangeDataProviderAndroid();
+}
+
+}  // namespace ui