Introduce fastbuild=2, which completely disables debug information.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 8e1e40c93241750d31a63318b0f271acc75ec171..1d24f27b7289a2c458dc4481a5e4b2cb80772f27 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -186,8 +186,9 @@
       # Override branding to select the desired branding flavor.
       'branding%': 'Chromium',
 
-      # Set to 1 to enable fast builds. It disables debug info for fastest
-      # compilation.
+      # Set to 1 to enable fast builds. Set to 2 for even faster builds
+      # (it disables debug info for fastest compilation - only for use
+      # on compile-only bots).
       'fastbuild%': 0,
 
       # Set to 1 to enable dcheck in release without having to use the flag.
@@ -1819,7 +1820,18 @@
           }, { # else clang!=1
             'conditions': [
               # For Windows and Mac, we don't genererate debug information.

[M-A Ruel, 2013/04/02 15:55:54]

The comments wasn't exact, please update.

-              ['OS=="win"', {
+              ['OS=="win" and fastbuild==2', {
+                # Completely disable debug information.
+                'msvs_settings': {
+                  'VCLinkerTool': {
+                    'GenerateDebugInformation': 'false',
+                  },
+                  'VCCLCompilerTool': {
+                    'DebugInformationFormat': '0',
+                  },
+                },
+              }],
+              ['OS=="win" and fastbuild==1', {
                 'msvs_settings': {
                   'VCLinkerTool': {
                     # This tells the linker to generate .pdbs, so that