Add Exception stack trace support to base.Log

Add Exception stack trace support to base.Log

When logging errors (Log.e), if the last argument is an exception,
its trace will be logged, like what happens with android.util.Log.

If the exception is used as argument for the format string, its
toString will be used in the message, then the trace will also be
printed, provided that it's the last argument.

BUG=474599
Committed: https://crrev.com/3c0c5b2708bc19d56ae4fc2609df0a2e5f3ff906
Cr-Commit-Position: refs/heads/master@{#324262}

[dgn, 2015-04-08 11:16:21]

dgn@chromium.org changed reviewers:
+ peter@chromium.org, yfriedman@chromium.org

[dgn, 2015-04-08 11:16:21]

PTAL

peter@: this should allow logging exceptions in your CL

Usage and output examples:

Log.FOO.e(TAG, "exception happened", new Exception("test"));

E/chromium.Foo: [FooTag] exception happened 
E/chromium.Foo: java.lang.Exception: test
E/chromium.Foo:  at org.chromium.chrome...

-----------------
Log.FOO.e(TAG, "exception happened %s", new Exception("test"));

E/chromium.Foo: [FooTag] exception happened java.lang.Exception: test
E/chromium.Foo: java.lang.Exception: test
E/chromium.Foo:  at org.chromium.chrome...

------------------
Log.FOO.e(TAG, "exception happened but should not log %s, %d", new
Exception("test"), 42);

E/chromium.Foo: [FooTag] exception happened but should not log
java.lang.Exception: test, 42

------------------
Log.FOO.e(TAG, "exception happened %d", 42, new Exception("test"));

E/chromium.Foo: [FooTag] exception happened 42
E/chromium.Foo: java.lang.Exception: test
E/chromium.Foo:  at org.chromium.chrome...

-------------------
Log.FOO.e(TAG, "no exception");
E/chromium.Foo: [FooTag] no exception

[Yaron, 2015-04-08 15:41:23]

joc: why only for error?

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
File base/android/java/src/org/chromium/base/Log.java (right):

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
base/android/java/src/org/chromium/base/Log.java:282: * @param args Arguments
referenced by the format specifiers in the format string.
Pls update

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
base/android/java/src/org/chromium/base/Log.java:287: if (args != null &&
args.length > 0 && args[args.length - 1] instanceof Exception) {
Nit: to be consistent, this should be Throwable

[dgn, 2015-04-08 16:19:02]

I had no real reason to make the change only for error, so I just made it
everywhere and added Log#wtf for consistency.

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
File base/android/java/src/org/chromium/base/Log.java (right):

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
base/android/java/src/org/chromium/base/Log.java:282: * @param args Arguments
referenced by the format specifiers in the format string.
On 2015/04/08 15:41:23, Yaron wrote:
> Pls update

Done.

https://codereview.chromium.org/1069373002/diff/1/base/android/java/src/org/c...
base/android/java/src/org/chromium/base/Log.java:287: if (args != null &&
args.length > 0 && args[args.length - 1] instanceof Exception) {
On 2015/04/08 15:41:23, Yaron wrote:
> Nit: to be consistent, this should be Throwable

Done.

[Yaron, 2015-04-08 16:32:06]

lgtm

[dgn, 2015-04-08 17:48:46]

The CQ bit was checked by dgn@chromium.org

[commit-bot: I haz the power, 2015-04-08 17:49:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1069373002/20001

[commit-bot: I haz the power, 2015-04-08 19:05:48]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-08 19:06:46]

Patchset 2 (id:??) landed as
https://crrev.com/3c0c5b2708bc19d56ae4fc2609df0a2e5f3ff906
Cr-Commit-Position: refs/heads/master@{#324262}