Make ScreenWakeLock ContextLifecycleObserver instead of LocalFrameLifecycleObserver

content/browser/wake_lock/wake_lock_browsertest.cc

Index: content/browser/wake_lock/wake_lock_browsertest.cc
diff --git a/content/browser/wake_lock/wake_lock_browsertest.cc b/content/browser/wake_lock/wake_lock_browsertest.cc
index 59e3ab71e1c0e168d3a7543725beafdf5517eee5..275b5e269bed9dec68d0dc6027190b62e4118a85 100644
--- a/content/browser/wake_lock/wake_lock_browsertest.cc
+++ b/content/browser/wake_lock/wake_lock_browsertest.cc
@@ -261,17 +261,6 @@ IN_PROC_BROWSER_TEST_F(WakeLockTest, KeepLockAfterInPageNavigation) {
   EXPECT_TRUE(HasWakeLock());
 }
 
-IN_PROC_BROWSER_TEST_F(WakeLockTest, UnlockAfterReload) {

[haraken, 2016/07/06 08:27:39]

This test is testing if the wake lock is gone after didCommitLoad is called.
We're replacing didCommitLoad with contextDestroyed, so the test doesn't make
sense.

[dcheng, 2016/07/06 08:34:42]

Hmm, isn't this still a useful thing to test? It's obvious if you look at the
code, but it's not bad to explicitly check this expectation in a test too.

[haraken, 2016/07/06 08:51:23]

Reload + WaitForLoadStop doesn't detach a document, so with this CL, the line
272 fails.

On the other hand, NavigateToURL detaches a document, so
UnlockAfterNavigationToSelf etc passes.

[alogvinov, 2016/07/06 08:58:58]

Is the problem that we are waiting for the wrong event, i.e. load stop vs
something that occurs later and does detach the document, or is the document not
detached at all during reload, so that wake lock is still true after reload?

[dcheng, 2016/07/06 09:04:12]

Assuming this is doing a "real" reload, the document should definitely be
detached.

As a quick sanity check:
- Is shell()->web_contents()->IsLoading() true after the Reload() call?
- Does WaitForLoadStop return true?

[haraken, 2016/07/06 09:14:35]

shell()->Reload();
fprintf(stderr, "%d\n", shell()->web_contents()->IsLoading());  // true
fprintf(stderr, "%d\n", WaitForLoadStop(GetWebContents()));  // true
fprintf(stderr, "%d\n", shell()->web_contents()->IsLoading());  // false
WaitForPossibleUpdate();  // Even after this call, Document::detach is not
called...

-  NavigateToURL(shell(), embedded_test_server()->GetURL("/simple_page.html"));
-  ScreenWakeLockInMainFrame();
-
-  shell()->Reload();
-  WaitForLoadStop(GetWebContents());
-
-  // Screen wake lock should be released after reload.
-  EXPECT_FALSE(HasWakeLock());
-}
-
 IN_PROC_BROWSER_TEST_F(WakeLockTest, BrowserInitiatedFrameNavigation) {
   NavigateToURL(shell(),
                 embedded_test_server()->GetURL("/frame_tree/2-4.html"));