Microdumps: support aarch64 and lib mapping from APK

Microdumps: support aarch64 and lib mapping from APK

- Filter modules by prot flags (only +x) not extensions. It wouldn't
  otherwise catch the case of Chrome mapping the library from the
  apk (which is mapped r-x but doesn't end in .so).
- Use compile-time detection of target arch, in order to cope with
  multilib OSes, where uname() doesn't reflect the run-time arch.
- Add OS information and CPU arch / count.
- Add support for aarch64.
- Add tests and stackwalk expectations for aarch64.
- Fix a potential overflow bug in the processor.
- Rebaseline the tests using smaller symbols.
- Fix microdump_writer_unittest.cc on 32-bit host.

BUG=chromium:410294

[primiano]

Hello!
I got fixes for aarch64 (plus some minor improvements).
Would you mind taking a look?
Thanks.

[mmandlis]

please, address my comment before committing.

lgtm

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
File src/processor/microdump_processor_unittest.cc (right):

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
src/processor/microdump_processor_unittest.cc:181:
TEST_F(MicrodumpProcessorTest, TestProcessArm64) {
could you, please, create a helper function here for all the successful
processing common code?

[primiano]

Done thanks.
Will land this later next week.

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
File src/processor/microdump_processor_unittest.cc (right):

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
src/processor/microdump_processor_unittest.cc:181:
TEST_F(MicrodumpProcessorTest, TestProcessArm64) {
On 2014/11/28 17:32:13, mmandlis wrote:
> could you, please, create a helper function here for all the successful
> processing common code? 

Done.

[mmandlis]

still lgtm.

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
File src/processor/microdump_processor_unittest.cc (right):

https://breakpad.appspot.com/2824002/diff/50004/src/processor/microdump_proce...
src/processor/microdump_processor_unittest.cc:181:
TEST_F(MicrodumpProcessorTest, TestProcessArm64) {
On 2014/11/28 18:32:38, primiano wrote:
> On 2014/11/28 17:32:13, mmandlis wrote:
> > could you, please, create a helper function here for all the successful
> > processing common code? 
> 
> Done.

Awesome. I think you can also use the AnalyzeDump method in
TestProcess_MissingSymbols. Sorry, I should have done it this way myself to
begin with.

[primiano]

Done.

Landed as r1407

(Also, yet again I used git svn dcommit instead of git cl dcommit, so the SVN
commit doesn't have the Review URL: ... my bad :/)