Fix an issue that drag and drop image always has default file name.

Fix an issue that drag and drop image always has default file name.

The reason is content::DropData is passed between renderer and browser
through IPC message, but we didn't declare several fields as
IPC_STRUCT_TRAITS.

Also noticed content::DropData.file_mime_types and
did_originate_from_renderer are also not declared. This CL didn't add
those in case it breaks something else.

BUG=702173
Review-Url: https://codereview.chromium.org/2803473003
Cr-Commit-Position: refs/heads/master@{#461942}
(cherry picked from commit 0b5c13253a5c567373cf037d336a998601105082)

Review-Url: https://codereview.chromium.org/2824803002 .
Cr-Commit-Position: refs/branch-heads/3029@{#735}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed: https://chromium.googlesource.com/chromium/src/+/1acc80de5dad9f57345eaa92b1da17212254e8cb

[xingliu, 2017-04-17 18:05:51]

Description was changed from

==========
Fix an issue that drag and drop image always has default file name.

The reason is content::DropData is passed between renderer and browser
through IPC message, but we didn't declare several fields as
IPC_STRUCT_TRAITS.

Also noticed content::DropData.file_mime_types and
did_originate_from_renderer are also not declared. This CL didn't add
those in case it breaks something else.

BUG=702173

Review-Url: https://codereview.chromium.org/2803473003
Cr-Commit-Position: refs/heads/master@{#461942}
(cherry picked from commit 0b5c13253a5c567373cf037d336a998601105082)
==========

to

==========
Fix an issue that drag and drop image always has default file name.

The reason is content::DropData is passed between renderer and browser
through IPC message, but we didn't declare several fields as
IPC_STRUCT_TRAITS.

Also noticed content::DropData.file_mime_types and
did_originate_from_renderer are also not declared. This CL didn't add
those in case it breaks something else.

BUG=702173

Review-Url: https://codereview.chromium.org/2803473003
Cr-Commit-Position: refs/heads/master@{#461942}
(cherry picked from commit 0b5c13253a5c567373cf037d336a998601105082)

Review-Url: https://codereview.chromium.org/2824803002 .
Cr-Commit-Position: refs/branch-heads/3029@{#735}
Cr-Branched-From:
939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed:
https://chromium.googlesource.com/chromium/src/+/1acc80de5dad9f57345eaa92b1da...
==========

[xingliu, 2017-04-17 18:05:52]

Committed patchset #1 (id:1) manually as
1acc80de5dad9f57345eaa92b1da17212254e8cb.