Move atrace enabling code from Chrome to WebView

Move atrace enabling code from Chrome to WebView

According to discussions, we decided to disable atrace for Chrome
because of the inaccuracy of timing in the trace due to the overhead
of atrace.

As WebView still needs atrace, move the atrace enabling code into
AwBrowserProcess.

BUG=trace-viewer:454
(https://code.google.com/p/trace-viewer/issues/detail?id=454)

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256186

[Yaron, 2014-03-06 21:24:15]

lgtm

istm like you could have a BUG= with some brief context on the change (i.e. what
you/Sami explained off-thread)

https://codereview.chromium.org/183183011/diff/1/base/android/java/src/org/ch...
File base/android/java/src/org/chromium/base/TraceEvent.java (right):

https://codereview.chromium.org/183183011/diff/1/base/android/java/src/org/ch...
base/android/java/src/org/chromium/base/TraceEvent.java:22: private static
volatile boolean sEnabled = false;
Can you comment distinguishing the difference b/w these

https://codereview.chromium.org/183183011/diff/1/base/android/java/src/org/ch...
base/android/java/src/org/chromium/base/TraceEvent.java:201: * @return True if
tracing is enabled, false otherwise.
update

[Xianzhu, 2014-03-06 21:54:41]

On 2014/03/06 21:24:15, Yaron wrote:
> lgtm
> 
> istm like you could have a BUG= with some brief context on the change (i.e.
what
> you/Sami explained off-thread)
> 

Done.

https://codereview.chromium.org/183183011/diff/1/base/android/java/src/org/ch...
File base/android/java/src/org/chromium/base/TraceEvent.java (right):

https://codereview.chromium.org/183183011/diff/1/base/android/java/src/org/ch...
base/android/java/src/org/chromium/base/TraceEvent.java:22: private static
volatile boolean sEnabled = false;
On 2014/03/06 21:24:16, Yaron wrote:
> Can you comment distinguishing the difference b/w these

Just found that we don't need a separate sATraceEnabled because
nativeStartATrace will enable chrome tracing, so calling
setEnabledToMatchNative() in setATraceEnabled is enough.

Added more comments for setATraceEnabled().

[Yaron, 2014-03-06 22:06:36]

much cleaner, thanks

[benm (inactive), 2014-03-07 08:38:02]

lgtm

thanks!

https://codereview.chromium.org/183183011/diff/30001/android_webview/java/src...
File android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
(right):

https://codereview.chromium.org/183183011/diff/30001/android_webview/java/src...
android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java:47:
final Class<?> traceClass = Class.forName("android.os.Trace");
maybe for a TODO after the initial move, but we could move this reflection out
of Chromium I think and do it in the Android tree (i.e. without reflection)
which would be neat :-)

[benm (inactive), 2014-03-07 08:38:47]

Do you have a full link to the bug? I don't know how to resolve trace-viewer:454
... :-(

[Xianzhu, 2014-03-07 17:21:37]

Added full issue link in description.

https://codereview.chromium.org/183183011/diff/30001/android_webview/java/src...
File android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java
(right):

https://codereview.chromium.org/183183011/diff/30001/android_webview/java/src...
android_webview/java/src/org/chromium/android_webview/AwBrowserProcess.java:47:
final Class<?> traceClass = Class.forName("android.os.Trace");
On 2014/03/07 08:38:03, benm wrote:
> maybe for a TODO after the initial move, but we could move this reflection out
> of Chromium I think and do it in the Android tree (i.e. without reflection)
> which would be neat :-)

Done.

[Xianzhu, 2014-03-07 17:21:42]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2014-03-07 17:21:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/183183011/50001

[commit-bot: I haz the power, 2014-03-07 17:27:05]

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

[commit-bot: I haz the power, 2014-03-07 17:27:06]

Try jobs failed on following builders: mac_chromium_compile_dbg

[Xianzhu, 2014-03-10 19:01:49]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2014-03-10 19:05:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/183183011/50001

[commit-bot: I haz the power, 2014-03-10 21:06:33]

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

[commit-bot: I haz the power, 2014-03-10 21:06:34]

Retried try job too often on android_dbg for step(s) slave_steps
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=android_db...

[Xianzhu, 2014-03-10 21:21:17]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2014-03-10 21:36:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/183183011/70001

[commit-bot: I haz the power, 2014-03-10 22:11:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/183183011/70001

[commit-bot: I haz the power, 2014-03-10 23:36:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/183183011/70001

[commit-bot: I haz the power, 2014-03-11 10:57:42]

Change committed as 256186