GN: Fix Android component build

build/config/BUILDCONFIG.gn

 # Copyright (c) 2013 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.
 
 # =============================================================================
 # BUILD FLAGS
 # =============================================================================
 #
 # This block lists input arguments to the build, along with their default
 # values. GN requires listing them explicitly so it can validate input and have
 # a central place to manage the build flags.
 #
 # If a value is specified on the command line, it will overwrite the defaults
 # given here, otherwise the default will be injected into the root scope.
 #
 # KEEP IN ALPHABETICAL ORDER and write a good description for everything.
 # Use "is_*" names for intrinsic platform descriptions and build modes, and
 # "use_*" names for optional features libraries, and configurations.
 declare_args() {
   # How many symbols to include in the build. This affects the performance of
   # the build since the symbols are large and dealing with them is slow.
   #   2 means regular build with symbols.
   #   1 means minimal symbols, usually enough for backtraces only.
   #   0 means no symbols.
   #   -1 means auto-set (off in release, regular in debug).
   symbol_level = -1
 
   # Component build.
-  is_component_build = false
+  is_component_build = os == "android"

[jamesr, 2014/10/20 23:11:24]

huh? why would this be the default? the production builds on android are not
component, nor is gyp

[cjhopman, 2014/10/21 00:19:06]

Yeah, the production builds also have is_debug = false, and on linux (I believe)
have is_clang = false.

I think the defaults should be set up for the best developer experience, rather
than be set up to match production builds. We have long wanted to change the
default on Android to be component builds (and is_clang=true by default, too).

That being said, this isn't an important part of this change. I'll take it out
and try to do it in a different change sometime and then we can focus discussion
about it there. 

I think the bot should use the component build since it's more strict, though,
so we'll just have to update the recipe for that.

   # Debug build.
   is_debug = true
 
   # Set to true when compiling with the Clang compiler. Typically this is used
   # to configure warnings.
   is_clang = (os == "mac" || os == "ios" || os == "linux")
 
   # Forces a 64-bit build on Windows. Does nothing on other platforms. Normally
   # we build 32-bit on Windows regardless of the current host OS bit depth.
   # Setting this flag will override this logic and generate 64-bit toolchains.
@@ skipping 661 matching lines @@
       if (defined(invoker.output_extension)) { output_extension = invoker.output_extension }
       if (defined(invoker.output_name)) { output_name = invoker.output_name }
       if (defined(invoker.public)) { public = invoker.public }
       if (defined(invoker.public_configs)) { public_configs = invoker.public_configs }
       if (defined(invoker.public_deps)) { public_deps = invoker.public_deps }
       if (defined(invoker.sources)) { sources = invoker.sources }
       if (defined(invoker.visibility)) { visibility = invoker.visibility }
     }
   }
 }