Rewrite clipboard write IPC handling to be easier to understand.

ui/base/clipboard/scoped_clipboard_writer.cc

Index: ui/base/clipboard/scoped_clipboard_writer.cc
diff --git a/ui/base/clipboard/scoped_clipboard_writer.cc b/ui/base/clipboard/scoped_clipboard_writer.cc
index 50a7ba39fec8544eec497a55c851387c578a3909..d1dc1b24645c136b921a83199def4569d63deba8 100644
--- a/ui/base/clipboard/scoped_clipboard_writer.cc
+++ b/ui/base/clipboard/scoped_clipboard_writer.cc
@@ -86,6 +86,23 @@ void ScopedClipboardWriter::WriteWebSmartPaste() {
   objects_[Clipboard::CBF_WEBKIT] = Clipboard::ObjectMapParams();
 }
 
+void ScopedClipboardWriter::WriteImage(const SkBitmap& bitmap) {
+  if (bitmap.drawsNothing()) {
+    NOTREACHED();
+    return;
+  }
+  bitmap_ = bitmap;
+  // TODO(dcheng): This is slightly less horrible than what we used to do, but
+  // only very slightly less.
+  SkBitmap* bitmap_pointer = &bitmap_;
+  Clipboard::ObjectMapParam packed_pointer;

[jamesr, 2014/09/22 22:38:41]

can you use bit_cast<Clipboard::ObjectMapParam>(&bitmap_) from base/macros.h ?

[dcheng, 2014/09/22 23:06:25]

I don't think I can use bit_cast directly here, because it wouldn't know how to
memcpy into std::vector's internal buffer.

+  for (size_t i = 0; i < sizeof(bitmap_pointer); ++i)

[jamesr, 2014/09/22 22:38:41]

oh god

[dcheng, 2014/09/22 23:06:25]

Yeah... I think that is the only appropriate response to this code. I still
think this is slightly better than the original version where we sent the
ClipboardObjectMap directly over the IPC message and then tried to do all sorts
of checks in the browser side to make sure it looked sane-ish. I've been
thinking about ideas to fix this insanity as well though in a followup patch.

+    packed_pointer.push_back(reinterpret_cast<uint8_t*>(&bitmap_pointer)[i]);
+  Clipboard::ObjectMapParams parameters;
+  parameters.push_back(packed_pointer);
+  objects_[Clipboard::CBF_SMBITMAP] = parameters;
+}
+
 void ScopedClipboardWriter::WritePickledData(
     const Pickle& pickle, const Clipboard::FormatType& format) {
   std::string format_string = format.Serialize();
@@ -106,6 +123,7 @@ void ScopedClipboardWriter::WritePickledData(
 void ScopedClipboardWriter::Reset() {
   url_text_.clear();
   objects_.clear();
+  bitmap_.reset();
 }
 
 void ScopedClipboardWriter::WriteTextOrURL(const base::string16& text,