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When a method has the @TraceEvent annotation, it will be transformed to include
TraceEvent.begin() and TraceEvent.end() at the start and end of the method.
The function body is moved to a new helper method, while the old function's new
body looks like the following:
```
TraceEvent.begin("Foo.bar");
try {
    wrappedByTraceEvent$bar();
    TraceEvent.end("Foo.bar");
} catch (Throwable e) {
    TraceEvent.end("Foo.bar");
    throw e;
}
```

Used the following code to test building various methods:
```
@TraceEvent
public static void basic() {}

@TraceEvent
public void takesArguments(boolean arg1, long arg2, float arg3) {}

@TraceEvent
public int returnsPrimitive(int arg1, byte arg2, Object arg3, TraceEvent arg4) {
    return 10;
}

@TraceEvent
public Object returnsObject(char arg1, short arg2, double arg3) {
    return null;
}

@TraceEvent
public int throwsError() throws Exception {
    throw new Exception();
}
```

Bug: 818267
Change-Id: I11127203662bf84de4a890da29a09676e760e621
Reviewed-on: https://chromium-review.googlesource.com/1066173
Commit-Queue: Tiger Oakes <tigero@google.com>
Reviewed-by: Biao She <bshe@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565624}