Upgrade MOCK_METHOD to googletest 1.10

(This is a merge of http://go/wvgerrit/139989.)

Googletest added a new, more powerful MOCK_METHOD() macro in 1.10. This
patch updates all our usage of the old MOCK_METHOD family to the new
macro. Full details can be found at
https://github.com/google/googletest/blob/release-1.10.0/googlemock/docs/cook_book.md#creating-mock-classes
but in brief, the new MOCK_METHOD() replaces the entire old MOCK_METHOD
family and has the following advantages:

1) No need to count parameters or update the macro name when changing
   parameters.
2) No need for a different macro for const methods.
3) The ability to specify override, noexcept, and other function
   qualifiers.
4) The macro order is now the same as C++ method definition order:
   Return Type -> Name -> Arguments -> Qualifiers

In addition to upgrading all our usage sites to the new macro, the
addition of the override qualifier to our MOCK_METHODs helped uncover
several cases where we were using MOCK_METHOD to override methods that
didn't exist. This is a great example of why the override qualifier is
so useful. These places have been updated, by removing the invalid and
unused mock method.

Bug: 207693687
Test: build_and_run_all_unit_tests
Change-Id: Iaad4a22c7f72bb48b1356fe01a41eb0a2f555244

libwvdrmengine/cdm/core/test/mock_clock.h

@@ -12,7 +12,7 @@ namespace wvcdm {
 
 class MockClock : public Clock {
  public:
-  MOCK_METHOD0(GetCurrentTime, int64_t());
+  MOCK_METHOD(int64_t, GetCurrentTime, (), (override));
 };
 
 // Frozen clock will always return the same value for the current time.