Fix up strings Sky passes to base/trace_event

Fix up strings Sky passes to base/trace_event

String parameters passed to the trace macros in base/trace_event must
either be std::string (which Sky doesn't use very much), pointers to
null terminated C-style strings that live forever (like a string
literal) pointers to C-style strings that are annotated by macro as
needing to be copied. This fixes up a few instances that passed pointers
to temporary strings without the copying annotation or pointers to
non-null-terminated strings so the trace data doesn't have random
garbage memory in it.

R=eseidel@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/59689550d58a02d0e76145f51a3587d96b87b329

[jamesr, 2015-04-29 00:12:46]

jamesr@chromium.org changed reviewers:
+ eseidel@chromium.org

[jamesr, 2015-04-29 00:12:46]

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/events/Gene...
File sky/engine/core/events/GenericEventQueue.cpp (right):

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/events/Gene...
sky/engine/core/events/GenericEventQueue.cpp:61:
TRACE_STR_COPY(event->type().ascii().data()));
event->type().ascii().data() is a pointer to temporary data that won't live past
the end of this function call, so it needs to be copied.

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/events/Gene...
sky/engine/core/events/GenericEventQueue.cpp:78:
TRACE_STR_COPY(event->type().ascii().data()),
ditto

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/events/Gene...
sky/engine/core/events/GenericEventQueue.cpp:121:
TRACE_STR_COPY(event->type().ascii().data()),
ditto

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/fetch/Resou...
File sky/engine/core/fetch/ResourceFetcher.cpp (right):

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/fetch/Resou...
sky/engine/core/fetch/ResourceFetcher.cpp:699:
TRACE_STR_COPY(resource->url().string().ascii().data()), "priority",
same here

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/frame/Traci...
File sky/engine/core/frame/Tracing.cpp (right):

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/frame/Traci...
sky/engine/core/frame/Tracing.cpp:24: // TRACE_EVENT_COPY_BEGIN0 needs a c-style
null-terminated string.
in particular, StringUTF8Adapter::data() doesn't return a pointer to a
null-terminated buffer

https://codereview.chromium.org/1107853003/diff/1/sky/engine/core/frame/Traci...
sky/engine/core/frame/Tracing.cpp:25: CString cstring(utf8.data(),
utf8.length());
this could be std::string as well. I figured CString is probably preferred here

[jamesr, 2015-04-29 17:10:05]

jamesr@chromium.org changed reviewers:
+ ojan@chromium.org

[eseidel, 2015-05-04 23:45:21]

lgtm

This seems really error prone.  I'm surprised Blink didn't do something nicer. 
We could consider a const char* String::traceCopy()?

[abarth-chromium, 2015-05-05 00:04:59]

On 2015/05/04 at 23:45:21, eseidel wrote:
> This seems really error prone.  I'm surprised Blink didn't do something nicer.
 We could consider a const char* String::traceCopy()?

Blink had something fancier, but we lost it when we switched to using base
tracing directly.

[jamesr, 2015-05-06 00:59:13]

Committed patchset #1 (id:1) manually as
59689550d58a02d0e76145f51a3587d96b87b329 (presubmit successful).