[DevTools] Remove V8InspectorSessionClient.

third_party/WebKit/Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'ContentDecryptionModuleResult.h',
@@ skipping 1102 matching lines @@
       'v8_inspector/V8RuntimeAgentImpl.cpp',
       'v8_inspector/V8RuntimeAgentImpl.h',
       'v8_inspector/V8StackTraceImpl.cpp',
       'v8_inspector/V8StackTraceImpl.h',
       'v8_inspector/V8StringUtil.cpp',
       'v8_inspector/V8StringUtil.h',
       'v8_inspector/public/V8ContextInfo.h',
       'v8_inspector/public/V8Inspector.h',
       'v8_inspector/public/V8InspectorClient.h',
       'v8_inspector/public/V8InspectorSession.h',
-      'v8_inspector/public/V8InspectorSessionClient.h',
       'v8_inspector/public/V8StackTrace.h',
       'web_memory_allocator_dump.cc',
       'web_memory_allocator_dump.h',
       'web_process_memory_dump.cc',
       'web_process_memory_dump.h',
       'weborigin/KURL.cpp',
       'weborigin/KURL.h',
       'weborigin/KURLHash.h',
       'weborigin/KnownPorts.cpp',
       'weborigin/KnownPorts.h',
@@ skipping 220 matching lines @@
       ['use_default_render_theme==1',
         {
           'platform_test_files': [
             'scroll/ScrollbarThemeAuraTest.cpp',
           ],
         }
       ],
     ],
   },
 }