Disable warning 4702: Unreachable code for the WPO/PGO builds.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 5510 matching lines @@
                   },
                 },
               }],
               ['optimize=="max"', {
                 # Disable Warning 4702 ("Unreachable code") for the WPO/PGO
                 # builds. Probably anything that this would catch that
                 # wouldn't be caught in a normal build isn't going to
                 # actually be a bug, so the incremental value of C4702 for
                 # PGO builds is likely very small.
                 'msvs_disabled_warnings': [
                   4702

[scottmg, 2016/05/28 18:46:43]

Why isn't this affecting pdfium on the PGO bot?

[Sébastien Marchand, 2016/05/28 18:53:50]

We're not using optimize=max on the PGO bot, we keep the default optimize value
for each target. 

                 ],
                 'msvs_settings': {
                   'VCCLCompilerTool': {
                     # 2, optimizeMaxSpeed, Maximize Speed (/O2)
                     'Optimization': '2',
                     # 1, favorSpeed - Favor fast code (/Ot)
                     'FavorSizeOrSpeed': '1',
                   },
                 },
                 # TODO(thakis): Remove clang==0 here, https://crbug.com/598772
@@ skipping 104 matching lines @@
           # TODO(brucedawson): http://crbug.com/554200 4312 is a VS
           # 2015 64-bit warning for integer to larger pointer
           4312,
 
           # TODO(brucedawson): http://crbug.com/593448 - C4595 is an 'illegal
           # inline operator new' warning that is new in VS 2015 Update 2.
           # This is equivalent to clang's no-inline-new-delete warning.
           # See http://bugs.icu-project.org/trac/ticket/11122
           4595,
         ],
+        'conditions': [
+          ['full_wpo_on_official==1', {
+            # Disable Warning 4702 ("Unreachable code") for the WPO/PGO
+            # builds. Probably anything that this would catch that
+            # wouldn't be caught in a normal build isn't going to
+            # actually be a bug, so the incremental value of C4702 for
+            # PGO builds is likely very small.
+            'msvs_disabled_warnings': [
+              4702
+            ],
+          }],
+        ],
         'msvs_settings': {
           'VCCLCompilerTool': {
             'AdditionalOptions': ['/MP'],
             'MinimalRebuild': 'false',
             'EnableFunctionLevelLinking': 'true',
             'RuntimeTypeInfo': 'false',
             'WarningLevel': '4',
             'WarnAsError': 'true',
             'DebugInformationFormat': '3',
             # ExceptionHandling must match _HAS_EXCEPTIONS above.
@@ skipping 634 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }