Re-land "Remove <(webrtc_root) from source file entries."

Changes differing from https://webrtc-codereview.appspot.com/37859004:
* I put the include_tests==1 stuff of audio_coding.gypi in its
  own audio_coding_tests.gypi file, including the Android and isolate
  targets which were incorrectly located in the previous CL
* I moved the bwe utilities in remote_bitrate_estimator.gypi
  into include_tests==1 since they depend on test.gyp after I
  cleaned up the duplicated inclusion of rtp_file_reader.cc

R=stefan@webrtc.org
TBR=tina.legrand@webrtc.org
TESTED=Passing gyp and compile using:
webrtc/build/gyp_webrtc -Dinclude_tests=1
webrtc/build/gyp_webrtc -Dinclude_tests=0
I also setup a Chromium checkout with my checkout mounted in
third_party/webrtc and ran build/gyp_chromium successfully.

BUG=4185

Review URL: https://webrtc-codereview.appspot.com/33159004

Cr-Commit-Position: refs/heads/master@{#8205}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8205 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/tools/tools.gyp b/webrtc/tools/tools.gyp
index 0a3d531..e2a5421 100644
--- a/webrtc/tools/tools.gyp
+++ b/webrtc/tools/tools.gyp
@@ -110,8 +110,16 @@
             '<(webrtc_root)/voice_engine/voice_engine.gyp:voice_engine',
           ],
           'sources': [
-            '<(webrtc_root)/modules/audio_processing/agc/test/agc_manager.cc',
-            '<(webrtc_root)/modules/audio_processing/agc/test/agc_manager.h',
+            'agc/agc_manager.cc',
+            'agc/agc_manager.h',
+          ],
+        },
+        {
+          'target_name': 'agc_test_utils',
+          'type': 'static_library',
+          'sources': [
+            'agc/test_utils.cc',
+            'agc/test_utils.h',
           ],
         },
         {
@@ -126,7 +134,7 @@
             'agc_manager',
           ],
           'sources': [
-            '<(webrtc_root)/modules/audio_processing/agc/test/agc_harness.cc',
+            'agc/agc_harness.cc',
           ],
         },  # agc_harness
         {
@@ -139,10 +147,10 @@
             '<(webrtc_root)/test/test.gyp:test_support',
             '<(webrtc_root)/system_wrappers/system_wrappers.gyp:system_wrappers_default',
             'agc_manager',
+            'agc_test_utils',
           ],
           'sources': [
-            '<(webrtc_root)/modules/audio_processing/agc/test/agc_test.cc',
-            '<(webrtc_root)/modules/audio_processing/agc/test/test_utils.cc',
+            'agc/agc_test.cc',
           ],
         },  # agc_proc
         {
@@ -154,7 +162,7 @@
             'agc_manager',
           ],
           'sources': [
-            '<(webrtc_root)/modules/audio_processing/agc/test/activity_metric.cc',
+            'agc/activity_metric.cc',
           ],
         },  # activity_metric
         {