MemorySanitizer: common.gypi changes.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 23bd721b125ec689a629a4986848caa8d049c1c7..adc137df4a11089f5c3b691d6e0d24af567d03af 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -278,6 +278,11 @@
       'tsan%': 0,
       'tsan_blacklist%': '<(PRODUCT_DIR)/../../tools/valgrind/tsan_v2/ignores.txt',
 
+      # Enable building with MSAN (Clang's -fsanitize=memory option).
+      # MemorySanitizer only works with clang, but msan=1 implies clang=1
+      # See http://clang.llvm.org/docs/MemorySanitizer.html
+      'msan%': 0,
+
       # Use a modified version of Clang to intercept allocated types and sizes
       # for allocated objects. clang_type_profiler=1 implies clang=1.
       # See http://dev.chromium.org/developers/deep-memory-profiler/cpp-object-type-identifier
@@ -715,6 +720,7 @@
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'mac_want_real_dsym%': '<(mac_want_real_dsym)',
     'asan%': '<(asan)',
+    'msan%': '<(msan)',
     'tsan%': '<(tsan)',
     'tsan_blacklist%': '<(tsan_blacklist)',
     'clang_type_profiler%': '<(clang_type_profiler)',
@@ -1049,7 +1055,7 @@
         'conditions': [
           # TODO(glider): set clang to 1 earlier for ASan and TSan builds so
           # that it takes effect here.
-          ['clang==0 and asan==0 and tsan==0', {
+          ['clang==0 and asan==0 and tsan==0 and msan==0', {
             # This will set gcc_version to XY if you are running gcc X.Y.*.
             # This is used to tweak build flags for gcc 4.5.
             'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
@@ -1476,6 +1482,9 @@
       ['tsan==1', {
         'clang%': 1,
       }],
+      ['msan==1', {
+        'clang%': 1,
+      }],
 
       ['OS=="linux" and clang_type_profiler==1', {
         'clang%': 1,
@@ -2928,6 +2937,31 @@
               }],
             ],
           }],
+          ['msan==1', {
+            'target_conditions': [
+              ['_toolset=="target"', {
+                'cflags': [
+                  '-fsanitize=memory',
+                  '-fsanitize-memory-track-origins',
+                  '-fno-omit-frame-pointer',
+                  '-fPIC',
+                ],
+                'ldflags': [
+                  '-fsanitize=memory',
+                ],
+                'defines': [
+                  'MEMORY_SANITIZER',
+                ],
+                'target_conditions': [
+                  ['_type=="executable"', {
+                    'ldflags': [
+                      '-pie',
+                    ],
+                  }],
+                ],
+              }],
+            ],
+          }],
           ['order_profiling!=0 and (chromeos==1 or OS=="linux" or OS=="android")', {
             'target_conditions' : [
               ['_toolset=="target"', {