Revert of [DevTools] Move DevToolsWindow testing code to a separate class.

Revert of [DevTools] Move DevToolsWindow testing code to a separate class. (https://codereview.chromium.org/395783002/)

Reason for revert:
Mac 10.7 has become flaky for ViewIDTest.Basic (http://build.chromium.org/p/chromium.mac/builders/Mac10.7%20Tests%20%282%29?numbuilds=100) and this CL is suspected as it touches this exact test.

Example crash stack trace below:

BrowserTestBase signal handler received SIGTERM. Backtrace:
0   browser_tests                       0x0132e9ba base::debug::StackTrace::StackTrace() + 26
1   browser_tests                       0x04e5ecb8 _ZN7content12_GLOBAL__N_1L27DumpStackTraceSignalHandlerEi + 72
2   libsystem_c.dylib                   0x9090259b _sigtramp + 43
3   ???                                 0xffffffff 0x0 + 4294967295
4   browser_tests                       0x01328f56 base::AtExitManager::RegisterCallback(void (*)(void*), void*) + 102
5   browser_tests                       0x02614bb4 Singleton\u003Ccc::TaskRunnerPairs, DefaultSingletonTraits\u003Ccc::TaskRunnerPairs>, cc::TaskRunnerPairs>::get() + 276
6   browser_tests                       0x026141e7 cc::BlockingTaskRunner::current() + 23
7   browser_tests                       0x02614762 cc::BlockingTaskRunner::CapturePostTasks::CapturePostTasks() + 18
8   browser_tests                       0x026404eb cc::SingleThreadProxy::Stop() + 59
9   browser_tests                       0x02619e04 cc::LayerTreeHost::~LayerTreeHost() + 132
10  browser_tests                       0x0261a2c1 cc::LayerTreeHost::~LayerTreeHost() + 17
11  browser_tests                       0x04011e94 ui::Compositor::~Compositor() + 148
12  browser_tests                       0x040120c1 ui::Compositor::~Compositor() + 17
13  browser_tests                       0x03fa8dfd -[BrowserCompositorViewCocoa .cxx_destruct] + 173
14  libobjc.A.dylib                     0x995863bf object_cxxDestructFromClass + 104
15  libobjc.A.dylib                     0x99583204 objc_destructInstance + 40
16  browser_tests                       0x021dd2c2 (anonymous namespace)::ZombieDealloc(objc_object*, objc_selector*) + 98
17  AppKit                              0x96b68b39 -[NSResponder dealloc] + 156
18  AppKit                              0x96b66fee -[NSView dealloc] + 74
19  libobjc.A.dylib                     0x9958254e _objc_rootRelease + 47
20  browser_tests                       0x03fa7f16 base::LazyInstance\u003Cbase::scoped_nsobject\u003CBrowserCompositorViewCocoa>, base::DefaultLazyInstanceTraits\u003Cbase::scoped_nsobject\u003CBrowserCompositorViewCocoa> > >::OnExit(void*) + 38
21  browser_tests                       0x013291e2 base::internal::Invoker\u003C1, base::internal::BindState\u003Cbase::internal::RunnableAdapter\u003Cvoid (*)(void*)>, void ()(void*), void ()(void*)>, void ()(void*)>::Run(base::internal::BindStateBase*) + 18
22  browser_tests                       0x01328e27 base::AtExitManager::ProcessCallbacksNow() + 119
23  browser_tests                       0x01328ec2 base::AtExitManager::~AtExitManager() + 34
24  browser_tests                       0x013bbb20 base::TestSuite::~TestSuite() + 48
25  browser_tests                       0x00b5f783 ChromeBrowserTestSuiteRunner::RunTestSuite(int, char**) + 51
26  browser_tests                       0x012fd642 (anonymous namespace)::ChromeTestLauncherDelegate::RunTestSuite(int, char**) + 34
27  browser_tests                       0x04e97e42 content::LaunchTests(content::TestLauncherDelegate*, int, int, char**) + 738
28  browser_tests                       0x012fd5f3 LaunchChromeTests(int, ChromeTestSuiteRunner*, int, char**) + 67
29  browser_tests                       0x00b5f73d main + 77
30  browser_tests                       0x00039635 start + 53
31  ???                                 0x0000000b 0x0 + 11

Original issue's description:
> [DevTools] Move DevToolsWindow testing code to a separate class.
> 
> This change:
> - allows for proper docking testing (including toolbox);
> - removes all test friends from DevToolsWindow;
> - unifies testing approach to use load callback instead of notifications;
> - adds simple toolbox tests.
> 
> BUG=393566
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284050

TBR=pfeldman@chromium.org,lushnikov@chromium.org,sky@chromium.org,dgozman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=393566
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284174

[gab, 2014-07-18 18:57:41]

Created Revert of [DevTools] Move DevToolsWindow testing code to a separate
class.

[commit-bot: I haz the power, 2014-07-18 18:58:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/gab@chromium.org/403833002/1

[commit-bot: I haz the power, 2014-07-18 19:00:37]

Change committed as 284174