Revert of Include sync.pb.h in sync_data.h.

Revert of Include sync.pb.h in sync_data.h. (https://chromiumcodereview.appspot.com/182313002/)

Reason for revert:
Broke win_x86_rel trybots about two thirds of the time (can't find sync.pb.h).  Appears that the build is non-deterministic, gonna need more testing.

Original issue's description:
> Include sync.pb.h in sync_data.h.
> 
> This change has two parts, including sync.pb.h in sync_data.h, and fixing
> gyp dependencies and header includes so that everything still builds.
> 
> Include sync.pb.h in sync_data.h in preparation for using AttachmentId
> (a protobuf in sync.pb.h) in sync_data.h. A forward declaration is
> insufficient because sync_data.h will be getting a typedef for vector<>
> of AttachmentId.
> 
> Several targets (transitively) depend on sync, however, their dependence
> is not properly modeled in gyp. Update dependencies and header includes
> so they can "see" sync.pb.h (a generated header) and any headers it
> includes.
> 
> Without these changes, four targets fail to build:
> 
> 1. extensions_browser - See extensions/extensions.gyp for the fix. Here's
> the compiler error:
> 
> In file included from ../../extensions/browser/extension_function.cc:10:
> In file included from ../../chrome/browser/extensions/extension_service.h:23:
> In file included from ../../chrome/browser/extensions/extension_sync_service.h:12:
> In file included from ../../chrome/browser/extensions/app_sync_bundle.h:15:
> In file included from ../../chrome/browser/extensions/app_sync_data.h:8:
> In file included from ../../chrome/browser/extensions/extension_sync_data.h:11:
> In file included from ../../sync/api/sync_change.h:13:
> ../../sync/api/sync_data.h:17:10: fatal error: 'sync/protocol/sync.pb.h' file not found
> 
> 
> 2. debugger - See chrome/chrome.gyp for the fix. Here's the compiler
> error:
> 
> In file included from ../../chrome/browser/devtools/browser_list_tabcontents_provider.cc:10:
> In file included from ../../chrome/browser/history/top_sites.h:13:
> In file included from ../../chrome/browser/history/history_service.h:26:
> In file included from ../../chrome/browser/history/delete_directive_handler.h:12:
> In file included from ../../sync/api/sync_change_processor.h:10:
> ../../sync/api/sync_data.h:17:10: fatal error: 'sync/protocol/sync.pb.h' file not found
> 
> 
> 3. apps - See chrome/chrome_browser_extensions.gypi for the fix. Here's
> the compiler error:
> 
> In file included from ../../apps/app_load_service.cc:12:
> In file included from ../../chrome/browser/extensions/extension_service.h:23:
> In file included from ../../chrome/browser/extensions/extension_sync_service.h:12:
> In file included from ../../chrome/browser/extensions/app_sync_bundle.h:15:
> In file included from ../../chrome/browser/extensions/app_sync_data.h:8:
> In file included from ../../chrome/browser/extensions/extension_sync_data.h:11:
> In file included from ../../sync/api/sync_change.h:13:
> ../../sync/api/sync_data.h:17:10: fatal error: 'sync/protocol/sync.pb.h' file not found
> 
> 
> 4. performance_ui_tests - See chrome/chrome_tests.gypi for the fix.
> Here's the compiler error:
> 
> In file included from ../../chrome/test/perf/generate_profile.cc:19:
> In file included from ../../chrome/browser/history/history_service.h:26:
> In file included from ../../chrome/browser/history/delete_directive_handler.h:12:
> In file included from ../../sync/api/sync_change_processor.h:10:
> In file included from ../../sync/api/sync_data.h:17:
> gen/protoc_out/sync/protocol/sync.pb.h:9:10: fatal error: 'google/protobuf/stubs/common.h' file not found
> 
> BUG=
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257666

TBR=tim@chromium.org,asargent@chromium.org,thakis@chromium.org,rsleevi@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257833

[maniscalco, 2014-03-19 00:28:17]

Created Revert of Include sync.pb.h in sync_data.h.

[commit-bot: I haz the power, 2014-03-19 00:30:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maniscalco@chromium.org/196423023/1

[commit-bot: I haz the power, 2014-03-19 00:30:55]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-19 00:30:56]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a lowly provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Lei Zhang, 2014-03-19 00:33:32]

lgtm stamp

[maniscalco, 2014-03-19 00:34:16]

The CQ bit was checked by maniscalco@chromium.org

[commit-bot: I haz the power, 2014-03-19 00:35:07]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maniscalco@chromium.org/196423023/1

[commit-bot: I haz the power, 2014-03-19 00:39:39]

Change committed as 257833