metrics: Add leak detector controller in Chrome OS metrics system

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 40bb44ed5ce810f947856024d47bacd62b68d2d6..0170597fd703cc9e0c6c34ba640173a9d83ecafc 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -1588,6 +1588,9 @@
     'libjpeg_ijg_gyp_path': '<(DEPTH)/third_party/libjpeg/libjpeg.gyp',
     'libjpeg_turbo_gyp_path': '<(DEPTH)/third_party/libjpeg_turbo/libjpeg.gyp',
 
+    # Enable runtime memory leak detector.
+    'enable_leak_detector%': 0,
+
     'conditions': [
       ['buildtype=="Official"', {
         # Continue to embed build meta data in Official builds, basically the
@@ -3082,6 +3085,9 @@
           'SAFE_BROWSING_DB_REMOTE',
         ],
       }],
+      ['enable_leak_detector==1 and chromeos==1', {
+        'defines': ['ENABLE_LEAK_DETECTOR=1'],

[brettw, 2016/02/18 21:14:57]

With the build flag system, this should not be necessary.

[Simon Que, 2016/02/19 02:13:02]

Done.

+      }],
     ],  # conditions for 'target_defaults'
     'target_conditions': [
       ['<(use_libpci)==1', {