audio policy: refine strategy invalidation logic

In checkOutputForAttributes(), only invalidate streams
if at least one client would move from output stream or we have
a dynamic policy installed.
Previous logic was systematically invalidating streams as soon as the
list of possible outputs for a given strategy had changed.
This avoids unnecessary playback disruptions when the route change can be
achieved by just selecting a new device on current output.

Bug: 132860590
Test: listen to visual voice mail and turn speaker phone on and off
Change-Id: Iee2d7cb336e1e699af4393e7d4aaef4cb266f265
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
index 83ae35e..a703861 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.cpp
@@ -5043,10 +5043,12 @@
     // also take into account external policy-related changes: add all outputs which are
     // associated with policies in the "before" and "after" output vectors
     ALOGVV("%s(): policy related outputs", __func__);
+    bool hasDynamicPolicy = false;
     for (size_t i = 0 ; i < mPreviousOutputs.size() ; i++) {
         const sp<SwAudioOutputDescriptor> desc = mPreviousOutputs.valueAt(i);
         if (desc != 0 && desc->mPolicyMix != NULL) {
             srcOutputs.add(desc->mIoHandle);
+            hasDynamicPolicy = true;
             ALOGVV(" previous outputs: adding %d", desc->mIoHandle);
         }
     }
@@ -5054,6 +5056,7 @@
         const sp<SwAudioOutputDescriptor> desc = mOutputs.valueAt(i);
         if (desc != 0 && desc->mPolicyMix != NULL) {
             dstOutputs.add(desc->mIoHandle);
+            hasDynamicPolicy = true;
             ALOGVV(" new outputs: adding %d", desc->mIoHandle);
         }
     }
@@ -5062,12 +5065,28 @@
         // get maximum latency of all source outputs to determine the minimum mute time guaranteeing
         // audio from invalidated tracks will be rendered when unmuting
         uint32_t maxLatency = 0;
+        bool invalidate = hasDynamicPolicy;
         for (audio_io_handle_t srcOut : srcOutputs) {
             sp<SwAudioOutputDescriptor> desc = mPreviousOutputs.valueFor(srcOut);
-            if (desc != 0 && maxLatency < desc->latency()) {
+            if (desc == nullptr) continue;
+
+            if (desc->isStrategyActive(psId) && maxLatency < desc->latency()) {
                 maxLatency = desc->latency();
             }
+
+            if (invalidate) continue;
+
+            for (auto client : desc->clientsList(false /*activeOnly*/)) {
+                const audio_io_handle_t newOutput = selectOutput(dstOutputs,
+                        client->flags(), client->config().format,
+                        client->config().channel_mask, client->config().sample_rate);
+                if (newOutput != srcOut) {
+                    invalidate = true;
+                    break;
+                }
+            }
         }
+
         ALOGV_IF(!(srcOutputs.isEmpty() || dstOutputs.isEmpty()),
               "%s: strategy %d, moving from output %s to output %s", __func__, psId,
               std::to_string(srcOutputs[0]).c_str(),
@@ -5075,7 +5094,9 @@
         // mute strategy while moving tracks from one output to another
         for (audio_io_handle_t srcOut : srcOutputs) {
             sp<SwAudioOutputDescriptor> desc = mPreviousOutputs.valueFor(srcOut);
-            if (desc != 0 && desc->isStrategyActive(psId)) {
+            if (desc == nullptr) continue;
+
+            if (desc->isStrategyActive(psId)) {
                 setStrategyMute(psId, true, desc);
                 setStrategyMute(psId, false, desc, maxLatency * LATENCY_MUTE_FACTOR,
                                 newDevices.types());
@@ -5091,8 +5112,10 @@
             selectOutputForMusicEffects();
         }
         // Move tracks associated to this stream (and linked) from previous output to new output
-        for (auto stream :  mEngine->getStreamTypesForProductStrategy(psId)) {
-            mpClientInterface->invalidateStream(stream);
+        if (invalidate) {
+            for (auto stream :  mEngine->getStreamTypesForProductStrategy(psId)) {
+                mpClientInterface->invalidateStream(stream);
+            }
         }
     }
 }