Build third-party code with -Wall, build chromium_code with -Wextra on Linux

third_party/ocmock/ocmock.gyp

Index: third_party/ocmock/ocmock.gyp
diff --git a/third_party/ocmock/ocmock.gyp b/third_party/ocmock/ocmock.gyp
index 04a4a885dac760bde6ef847d1df8b85b41f15fa7..942992bb9273e28d2cc31e5d8473568ba5197690 100644
--- a/third_party/ocmock/ocmock.gyp
+++ b/third_party/ocmock/ocmock.gyp
@@ -72,6 +72,12 @@
             'OCMock/OCObserverMockObject.h',
             'OCMock/OCObserverMockObject.m',
           ],
+          'variables': {
+            'clang_warning_flags': [
+              # NSInvocation+OCMAdditions.m has some `- (void) foo; {...`
+              '-Wno-semicolon-before-method-body',
+            ],
+          },
         },
       ],
     }],