Merge "CDD: Requirements for Heavyweight app mode" into pi-dev
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+## 3.17\. Heavyweight Apps
+
+If device implementations declare the feature [`FEATURE_CANT_SAVE_STATE`](
+https://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_CANT_SAVE_STATE),
+then they:
+
+* [C-1-1] MUST have only one installed app that specifies
+ [`cantSaveState`](https://developer.android.com/reference/android/R.attr#cantSaveState)
+ running in the system at a time. If the user
+ leaves such an app without explicitly exiting it (for example by pressing
+ home while leaving an active activity the system, instead of pressing back
+ with no remaining active activities in the system), then
+ device implementations MUST prioritize that app in RAM as they do for other
+ things that are expected to remain running, such as foreground services.
+ While such an app is in the background, the system can still apply power
+ management features to it, such as limiting CPU and network access.
+* [C-1-2] MUST provide a UI affordance to chose the app that won't
+ participate in the normal state save/restore mechanism once the user
+ launches a second app declared with [`cantSaveState`](https://developer.android.com/reference/android/R.attr#cantSaveState)
+ attribute.
+* [C-1-3] MUST NOT apply other changes in policy to apps that specify
+ [`cantSaveState`](https://developer.android.com/reference/android/R.attr#cantSaveState),
+ such as changing CPU performance or changing scheduling prioritization.
+
+If device implementations don't declare the feature [`FEATURE_CANT_SAVE_STATE`](
+https://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_CANT_SAVE_STATE),
+then they:
+
+* [C-1-1] MUST ignore the [`cantSaveState`](https://developer.android.com/reference/android/R.attr#cantSaveState)
+ attribute set by apps and MUST NOT change the app behavior based on that
+ attribute.
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