Add a TestBrowserDialog helper class for testing browser dialogs in a consistent way.

base/test/test_timeouts.h

Index: base/test/test_timeouts.h
diff --git a/base/test/test_timeouts.h b/base/test/test_timeouts.h
index ddaf05b5e0ca583b011f19bb237817aa01a5c953..d662a201dd6282a829bc0751d97c8b1429f37544 100644
--- a/base/test/test_timeouts.h
+++ b/base/test/test_timeouts.h
@@ -13,6 +13,9 @@
 // the timeouts for different environments (like Valgrind).
 class TestTimeouts {
  public:
+  // Argument that can be passed on the command line to indicate "no timeout".
+  static const char kNoTimeoutSwitchValue[];

[Peter Kasting, 2016/12/15 08:12:29]

Nit: Can this be declared constexpr?  Maybe by moving the initializer value
here?  (Probably still needs a definition point in the .cc file in that case to
link correctly)

[tapted, 2016/12/16 04:21:53]

Done. Although (curiously?) Clang was happy with just `constexpr`, but MSVC
required `constexpr const`.

With just `constexpr` MSVC emits:

test_timeouts.h(17):error C2131: expression did not evaluate to a constant
test_timeouts.h(17): note: failure was caused by unevaluable pointer value

This looks kinda like
https://connect.microsoft.com/VisualStudio/feedback/details/1290476

"half-solved in Visual Studio 2015 Update 1"

Except according to http://crrev.com/417157 we are already using VS 2015 Update
3 as of Sep 7, 2016. But the example code there is using `constexpr const`.


Seems MSVC accepts the following:

  static constexpr char kNoTimeoutSwitchValue[] = { '-', '1', '\0' };

(gross). But not this:

  static constexpr char kNoTimeoutSwitchValue[] = "-1";

However, it *does*  accept "constexpr const":

  static constexpr const char kNoTimeoutSwitchValue[] = "-1";


Also, with the first version, it seems to be "impossible" to provide a
*definition* with MSVC. 
c:\src\devel\git\chromium\src\base\test\test_timeouts.cc(71): error C2373:
'kNoTimeoutSwitchValue': redefinition; different type modifiers
c:\src\devel\git\chromium\src\base\test\test_timeouts.h(17): note: see
declaration of 'kNoTimeoutSwitchValue'

or

test_timeouts.cc(71): error C2734: 'TestTimeouts::kNoTimeoutSwitchValue':
'const' object must be initialized if not 'extern'

or

test_timeouts.cc(71): error C2374: 'kNoTimeoutSwitchValue': redefinition;
multiple initialization

And actually MSVC will link without a definition at all. However, Clang will
not.

However, "constexpr const" seems to make all the compilers happy.

[Peter Kasting, 2016/12/16 06:30:56]

That's all very weird... when I tested something similar the other day constexpr
char foo[] = "test"; worked for me, IIRC, but shrug.

+
   // Initializes the timeouts. Non thread-safe. Should be called exactly once
   // by the test suite.
   static void Initialize();