Add SetImageData api to chrome.clipboard.

chrome/browser/extensions/clipboard_extension_helper.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 "chrome/browser/extensions/clipboard_extension_helper.h"
+
+#include "base/macros.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/synchronization/cancellation_flag.h"
+#include "chrome/browser/image_decoder.h"
+#include "extensions/browser/api/clipboard/clipboard_api.h"
+#include "ui/base/clipboard/scoped_clipboard_writer.h"
+
+using content::BrowserThread;
+
+namespace extensions {
+
+class ClipboardExtensionHelper::ClipboardImageDataDecoder
+    : public ImageDecoder::ImageRequest {
+ public:
+  explicit ClipboardImageDataDecoder(
+      const base::WeakPtr<ClipboardExtensionHelper>& owner)
+          : owner_(owner) {}
+
+  void Start(const std::vector<char>& image_data, clipboard::ImageType type) {
+    DCHECK_CURRENTLY_ON(BrowserThread::UI);
+    std::string image_data_str(image_data.begin(), image_data.end());
+
+    ImageDecoder::ImageCodec codec = ImageDecoder::DEFAULT_CODEC;
+#if defined(OS_CHROMEOS)

[Devlin, 2016/12/09 15:23:43]

Is this API only supported on CrOS?  If so, can't we make this file CrOS-only?

[jennyz, 2016/12/14 01:15:36]

Yes, this API is Cros-only, I made a couple of changes to make the related files
CrOS-only, including this file.

+    if (type == clipboard::IMAGE_TYPE_PNG) {

[Devlin, 2016/12/09 15:23:43]

prefer a switch

[jennyz, 2016/12/14 01:15:35]

Done.

+      codec = ImageDecoder::ROBUST_PNG_CODEC;
+    } else if (type == clipboard::IMAGE_TYPE_JPEG) {
+      codec = ImageDecoder::ROBUST_JPEG_CODEC;
+    } else {
+      OnDecodeImageFailed();
+      return;
+    }
+#endif
+
+    ImageDecoder::StartWithOptions(this, image_data_str, codec, true);
+  }
+
+  void Cancel() {

[Devlin, 2016/12/09 15:23:48]

Shouldn't we also call ImageDecoder::Cancel()?

[jennyz, 2016/12/14 01:15:35]

Yes, good suggestion. Now I changed to call ImageDecoder::Cancel() and get rid
of cancel_flag_.

+    cancel_flag_.Set();
+    if (owner_)
+      owner_->OnImageDecodeCancel();
+  }
+
+  void OnImageDecoded(const SkBitmap& decoded_image) override {
+    if (!cancel_flag_.IsSet() && owner_)

[Devlin, 2016/12/09 15:23:45]

If we *do* want this approach, instead of doing this, we could just null out
owner_ in Cancel().

[jennyz, 2016/12/14 01:15:35]

Changed to use unique_ptr to manage the life cycle. No need to check owner_ on
callback.

+      owner_->OnImageDecoded(decoded_image);
+    delete this;
+  }
+
+  void OnDecodeImageFailed() override {
+    if (!cancel_flag_.IsSet() && owner_)
+      owner_->OnImageDecodeFailure();
+    delete this;
+  }
+
+ private:
+  ~ClipboardImageDataDecoder() override {}
+  base::WeakPtr<ClipboardExtensionHelper> owner_;

[Devlin, 2016/12/09 15:23:48]

What was wrong with dcheng's suggestion to have the lifetime managed?

https://codereview.chromium.org/2379573008/diff/100001/chrome/browser/extensi...

[jennyz, 2016/12/14 01:15:36]

Yes, changed to use unique_ptr to manage the lifetime.

+  base::CancellationFlag cancel_flag_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClipboardImageDataDecoder);
+};
+
+ClipboardExtensionHelper::ClipboardImageDataDecoder*
+    ClipboardExtensionHelper::clipboard_image_data_decoder_;
+
+ClipboardExtensionHelper::ClipboardExtensionHelper()
+    : clipboard_writer_(
+          new ui::ScopedClipboardWriter(ui::CLIPBOARD_TYPE_COPY_PASTE)),
+          weak_factory_(this) {}
+
+ClipboardExtensionHelper::~ClipboardExtensionHelper() {}
+
+void ClipboardExtensionHelper::DecodeAndSaveImageData(
+    const std::vector<char>& data,
+    api::clipboard::ImageType type,
+    const base::Closure& success_callback,
+    const base::Closure& error_callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  // If there is a previous image decoding request still running, cancel it
+  // first. We only need the most recent image save request be completed.
+  if (clipboard_image_data_decoder_)
+    clipboard_image_data_decoder_->Cancel();

[Devlin, 2016/12/09 15:23:47]

So only one item can be using the decode api at any time?  Why is that?

[jennyz, 2016/12/14 01:15:35]

The clipboard can only save one image from the SetImageData call, which should
be the most recent request in the multiple paste actions cases. Therefore, no
need to get the results from the previous decode api calls.

+
+  // clipboard_image_data_decoder_ will manage its own lifetime.
+  clipboard_image_data_decoder_ = new ClipboardImageDataDecoder(
+      weak_factory_.GetWeakPtr());
+  image_save_success_callback_ = success_callback;
+  image_save_error_callback_ = error_callback;
+  clipboard_image_data_decoder_->Start(data, type);
+}
+
+void ClipboardExtensionHelper::OnImageDecodeFailure() {
+  clipboard_image_data_decoder_ = nullptr;
+  image_save_error_callback_.Run();

[Devlin, 2016/12/09 15:23:46]

prefer using base::ResetAndReturn or a OnceCallback. (ditto for other callbacks)

[jennyz, 2016/12/14 01:15:35]

Done.

+}
+
+void ClipboardExtensionHelper::OnImageDecoded(const SkBitmap& bitmap) {
+  clipboard_image_data_decoder_ = nullptr;
+
+  // Write the decoded image data to clipboard.
+  if (!bitmap.empty() && !bitmap.isNull())
+    clipboard_writer_->WriteImage(bitmap);
+  clipboard_writer_.reset(
+      new ui::ScopedClipboardWriter(ui::CLIPBOARD_TYPE_COPY_PASTE));
+
+  image_save_success_callback_.Run();
+}
+
+void ClipboardExtensionHelper::OnImageDecodeCancel() {
+  image_save_error_callback_.Run();
+}
+
+}  // namespace extensions