Fix Chromoting Android client crashed on launch

Fix Chromoting Android client crashed on launch

We crash because mRefreshButton is null when updateUI() is called.
mRefreshButton is initialized on onCreateOptionsMenu()

According to http://stackoverflow.com/questions/13267030/oncreateoptionsmenu-is-never-called, seems like 
onCreateOptionMenu will never got called on some themes on phones with menu button.

I can repro by overriding the theme to @android:style/Theme.Black.NoTitleBar

The fix is adding a null check.

BUG=364591
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274354

[Sergey Ulanov, 2014-06-01 03:45:52]

Please update CL description to follow the format suggested here:
http://dev.chromium.org/developers/contributing-code#TOC-Change-List-Descript...
Particularly first line should be a summary of the change, e.g. "Fix Chromoting
Android client crash" (that's useful for some SCM tools, such as gitk). Also
it's not necessary to duplicate information that's already in the linked bug,
e.g. callstack.

[Lambros, 2014-06-02 17:07:22]

lgtm when description is updated. Please see comment as well.

https://codereview.chromium.org/308793007/diff/1/remoting/android/java/src/or...
File remoting/android/java/src/org/chromium/chromoting/Chromoting.java (right):

https://codereview.chromium.org/308793007/diff/1/remoting/android/java/src/or...
remoting/android/java/src/org/chromium/chromoting/Chromoting.java:399: if
(mRefreshButton != null) {
Looks like there's a race between updateUi() and onCreateOptionsMenu(). This is
the right fix here, but I wonder if we need to do anything in
onCreateOptionsMenu() to ensure the button is initially created in the right
state? Probably not, but worth checking anyway?

[kelvinp, 2014-06-02 18:57:05]

The CQ bit was checked by kelvinp@chromium.org

[commit-bot: I haz the power, 2014-06-02 18:58:56]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kelvinp@chromium.org/308793007/1

[commit-bot: I haz the power, 2014-06-02 22:26:24]

Change committed as 274354