Disables mic bump-up level if not built with chromium

In http://chromegw.corp.google.com/viewvc/chrome-internal?view=rev&revision=61016 a feature to bump up low input audio levels to a fixed value of 33%. In https://webrtc-codereview.appspot.com/43109004/ a configuration to choose an arbitrary level was added, but still using 33% as default.
The original bump-up feature was added to fix audio issues in chrome, but affected also non-chrome users. This CL disables the feature for non-chrome applications.

Note that the default value is set to 0, but any value up to 12 will do. Zero was selected because it is more clear that the feature is turned off.

BUG=4529
R=andrew@webrtc.org, tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43259004

Cr-Commit-Position: refs/heads/master@{#9048}
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index f91d53a..63c70f7 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -78,7 +78,11 @@
 // [12, 255]. Here, 255 maps to 100%.
 //
 // Must be provided through AudioProcessing::Create(Confg&).
+#if defined(WEBRTC_CHROMIUM_BUILD)
 static const int kAgcStartupMinVolume = 85;
+#else
+static const int kAgcStartupMinVolume = 0;
+#endif  // defined(WEBRTC_CHROMIUM_BUILD)
 struct ExperimentalAgc {
   ExperimentalAgc() : enabled(true), startup_min_volume(kAgcStartupMinVolume) {}
   ExperimentalAgc(bool enabled)
diff --git a/webrtc/tools/agc/agc_manager_unittest.cc b/webrtc/tools/agc/agc_manager_unittest.cc
index e126c01..c379d2d 100644
--- a/webrtc/tools/agc/agc_manager_unittest.cc
+++ b/webrtc/tools/agc/agc_manager_unittest.cc
@@ -388,8 +388,13 @@
 
 TEST_F(AgcManagerUnitTest, LowInitialVolumeIsRaised) {
   ExpectCheckVolumeAndReset(11u);
-  // Should set MicVolume to kMinInitMicLevel = 85.
+#if defined(WEBRTC_CHROMIUM_BUILD)
+  // Should set MicVolume to kMinInitMicLevel = 85 if built with Chromium.
   EXPECT_CALL(volume_, SetMicVolume(Eq(85u))).WillOnce(Return(0));
+#else
+  // Otherwise it will raise to the kMinMicLevel = 12.
+  EXPECT_CALL(volume_, SetMicVolume(Eq(12u))).WillOnce(Return(0));
+#endif
   PostProcCallback(1);
   EXPECT_CALL(*agc_, GetRmsErrorDb(_))
     .WillOnce(Return(false));